mDNS seems to cause trouble with ArduinoOTA

[milkpirate]

I am having trouble with ArduinoOTA which seems to be caused by mDNS:

Minimal example - Arduini IDE 1.8.8:

#include <ArduinoOTA.h>
#include <Streaming.h>

void setup()
{
  Serial.begin(74880);
  delay(1);   // esp doesnt like writing to serial right away

  Serial<<endl<<endl;
  Serial<<F("Build date/time:         " __DATE__ " / " __TIME__)<<endl;
  Serial<<F("Reset info:              ")<<ESP.getResetInfo()<<endl;
  Serial<<F("Boot mode:               ")<<ESP.getBootMode()<<endl;
  Serial<<F("Boot version:            ")<<ESP.getBootVersion()<<endl;
  Serial<<F("Reset cause:             ")<<ESP.getResetReason()<<endl;
  Serial<<F("CPU frequency (MHz):     ")<<ESP.getCpuFreqMHz()<<endl;
  Serial<<F("Core version:            ")<<ESP.getCoreVersion()<<endl;
  
  Serial<<F("SDK version:             ")<<ESP.getSdkVersion()<<endl;
  Serial<<F("Flash chip mode:         ")<<ESP.getFlashChipMode()<<endl;
  Serial<<F("Flash size (by SDK):     ")<<ESP.getFlashChipSize()<<endl;
  Serial<<F("Flash size (by chip ID): ")<<ESP.getFlashChipRealSize()<< endl;
  Serial<<F("Flash speed (MHz):       ")<<ESP.getFlashChipSpeed()/1000000<<endl;
  
  Serial<<F("Sketch size/left:        ")<<ESP.getSketchSize()<<F(" / ") << ESP.getFreeSketchSpace()<<endl;
  Serial<<F("Sketch usage:            ")<<(ESP.getFreeSketchSpace()+ESP.getSketchSize())/ESP.getSketchSize()<<F("%")<<endl;
  Serial<<F("Sketch MD5:              ")<<ESP.getSketchMD5()<<endl;
  Serial<<F("Free heap:               ")<<ESP.getFreeHeap()<<endl; 

  Serial<<endl<<"start ota";
  
  ArduinoOTA.setHostname("espOTA");  // Hostname defaults
  ArduinoOTA.begin();
}


void loop() {
  ArduinoOTA.handle();
}

Serial:

 ets Jan  8 2013,rst cause:2, boot mode:(3,7)

load 0x4010f000, len 1384, room 16 
tail 8
chksum 0x2d
csum 0x2d
v0fd86a07
~ld


Build date/time:         Jan 21 2019 / 20:08:24
Reset info:              Fatal exception:0 flag:6 (EXT_SYS_RST) epc1:0x00000000 epc2:0x00000000 epc3:0x00000000 excvaddr:0x00000000 depc:0x00000000
Boot mode:               1
Boot version:            31
Reset cause:             External System
CPU frequency (MHz):     80
Core version:            2_5_0_BETA2
SDK version:             3.0.0-dev(c0f7b44)
Chip ID:                 0xE3232C
Flash ID:                0x1640E0
Flash chip mode:         0
Flash size (by SDK):     4194304
Flash size (by chip ID): 4194304
Flash speed (MHz):       40
Sketch size/left:        361008 / 3829760
Sketch usage:            11%
Sketch MD5:              6fb3b7badf1313bcb2d3276daed7dcd8
Free heap:               48760

start ota
...

Stack trace:

its not always the same it differs from boot to boot but its always related to some mDNS methods:

Exception 9: LoadStoreAlignmentCause: Load or store to an unaligned address
PC: 0x4020689f: esp8266::MDNSImplementation::MDNSResponder::_parseMessage() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 119
EXCVADDR: 0x40206977: esp8266::MDNSImplementation::MDNSResponder::_process(bool) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 74

Decoding stack results
0x40206998: esp8266::MDNSImplementation::MDNSResponder::_callProcess() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Helpers.cpp line 175
0x4020b9af: std::_Function_handler    (esp8266::MDNSImplementation::MDNSResponder*)> >::_M_invoke(std::_Any_data const&) at c:\users\<user>\documents\arduinodata\packages\esp8266\tools\xtensa-lx106-elf-gcc\2.5.0-3-20ed2b9\xtensa-lx106-elf\include\c++\4.8.2/functional line 2073
0x40202e5e: std::function ::operator()() const at c:\users\<user>\documents\arduinodata\packages\esp8266\tools\xtensa-lx106-elf-gcc\2.5.0-3-20ed2b9\xtensa-lx106-elf\include\c++\4.8.2/functional line 2465
0x40202ea4: UdpContext::_s_recv(void*, udp_pcb*, pbuf*, ip4_addr const*, unsigned short) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266WiFi\src/include/UdpContext.h line 423
0x401002b0: pvPortMalloc at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\heap.c line 153
0x4021afcc: udp_input at core/udp.c line 404
0x401007fc: malloc at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\umm_malloc\umm_malloc.c line 1673
0x40220000: raw_input at core/raw.c line 187
0x4021f0c0: ip4_input at core/ipv4/ip4.c line 704
0x401005ac: _umm_free at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\umm_malloc\umm_malloc.c line 1300
0x40217041: ethernet_input_LWIP2 at netif/ethernet.c line 188
0x40216e77: esp2glue_ethernet_input at glue-lwip/lwip-git.c line 422
0x40236442: ethernet_input at glue-esp/lwip-esp.c line 363
0x40236453: ethernet_input at glue-esp/lwip-esp.c line 371
0x40208b8c: esp8266::MDNSImplementation::MDNSResponder::_udpAppendBuffer(unsigned char const*, unsigned int) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1036
0x40208bba: esp8266::MDNSImplementation::MDNSResponder::_udpAppend8(unsigned char) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1048
0x40208cfd: esp8266::MDNSImplementation::MDNSResponder::_write8(unsigned char, esp8266::MDNSImplementation::MDNSResponder::stcMDNSSendParameter&) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1176
0x40208f39: esp8266::MDNSImplementation::MDNSResponder::_writeMDNSHostDomain(char const*, bool, esp8266::MDNSImplementation::MDNSResponder::stcMDNSSendParameter&) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1289
0x40208c0e: esp8266::MDNSImplementation::MDNSResponder::_udpAppend32(unsigned int) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1066
0x40208d29: esp8266::MDNSImplementation::MDNSResponder::_write16(unsigned short, esp8266::MDNSImplementation::MDNSResponder::stcMDNSSendParameter&) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1186
0x4020920d: esp8266::MDNSImplementation::MDNSResponder::_writeMDNSAnswer_PTR_IP4(IPAddress, esp8266::MDNSImplementation::MDNSResponder::stcMDNSSendParameter&) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1421
0x40216a31: glue2esp_linkoutput at glue-esp/lwip-esp.c line 299
0x40216cb3: new_linkoutput at glue-lwip/lwip-git.c line 233
0x402170c8: ethernet_output at netif/ethernet.c line 312
0x4021e7f9: etharp_output_LWIP2 at core/ipv4/etharp.c line 896
0x4020b535: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 124
0x4020b524: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 120
0x4020b518: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 117
0x401005ac: _umm_free at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\umm_malloc\umm_malloc.c line 1300
0x401009f0: free at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\umm_malloc\umm_malloc.c line 1760
0x4021fdf0: mem_free at core/mem.c line 237
0x40206964: esp8266::MDNSImplementation::MDNSResponder::_process(bool) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 84
0x40204efc: esp8266::MDNSImplementation::MDNSResponder::update() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS.cpp line 1077
0x402038b6: ArduinoOTAClass::handle() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ArduinoOTA\ArduinoOTA.cpp line 366
0x4020b4ad: esp_schedule() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 95
0x4020b53e: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 127

Stack dump:

Exception (9):
epc1=0x4020689f epc2=0x00000000 epc3=0x00000000 excvaddr=0x40206977 depc=0x00000000

>>>stack>>>

ctx: sys
sp: 3fffec60 end: 3fffffb0 offset: 01a0
3fffee00:  72616843 69646279 3ffe0073 00000000  
3fffee10:  00000001 00000000 4000050c 00000000  
3fffee20:  40223a0d 0000001f 4010508d 4000050c  
3fffee30:  401051d0 006261b9 3fff0344 00000000  
3fffee40:  3ffee260 3ffef1f4 00000000 402283db  
3fffee50:  00000000 0045c581 40228446 3fff05bc  
3fffee60:  3fff05ee 00000000 3fff0344 40206998  
3fffee70:  00000011 00000001 00000020 4020b9af  
3fffee80:  00000000 10310606 00640100 40202e5e  
3fffee90:  3fff05ee 00000000 3fff038c 40202ea4  
3fffeea0:  00000065 401002b0 3fff038c 4021afcc  
3fffeeb0:  000014e9 3ffeef94 3ffeef94 401007fc  
3fffeec0:  40220000 00000065 3fffef30 3ffeef94  
3fffeed0:  3ffef03c 3fff05bc 3fff05da 4021f0c0  
3fffeee0:  00000014 00000000 3ffeef94 401005ac  
3fffeef0:  3fffdc80 3ffef5a4 3fff04fc 3ffef5ec  
3fffef00:  00000008 3ffeef94 3fff05bc 40217041  
3fffef10:  3fffdc80 3ffef5a4 3fff04fc 40216e77  
3fffef20:  40236442 3ffef5a4 3fff04fc 40236453  
3fffef30:  3fff05cc 3fff05bc 00000002 3ffe85e8  
3fffef40:  4023112f 00000000 3fff04fc 402380bf  
3fffef50:  40000f49 3fffdab0 3fffdab0 40000f49  
3fffef60:  40000e19 40001878 00000004 3fffffb0  
3fffef70:  3fffff10 aa55aa55 000000ba 401048b4  
3fffef80:  401048ba 00000004 3fffffb0 40104424  
3fffef90:  4010000d 00000002 00000000 b94f2195  
3fffefa0:  00000000 3fffef3c 00000000 3fffff58  
3fffefb0:  3fffffc0 00000000 00000000 feefeffe  
3fffefc0:  feefeffe feefeffe feefeffe feefeffe
...
3ffffa50:  feefeffe feefeffe feefeffe feefeffe  
3ffffa60:  00000001 feefeffe feefeffe feefeffe  
3ffffa70:  feefeffe feefeffe feefeffe 0000000c  
3ffffa80:  3ffef6ec 3ffee92c 00000001 40208b8c  
3ffffa90:  feefeffe feefeffe 3fffff00 40208bba  
3ffffaa0:  feef020c feefeffe feefeffe feefeffe  
3ffffab0:  feefeffe feefeffe 3fffff00 40208cfd  
3ffffac0:  feefeffe feefeffe 3fffff00 40208f39  
3ffffad0:  00000000 00000000 00000000 00000000  
3ffffae0:  00000000 00000000 00000000 00000000  
3ffffaf0:  00000000 00000000 00000000 00000000  
3ffffb00:  00000000 00000000 00000000 00000000  
3ffffb10:  00000000 00000000 00000000 00000000  
3ffffb20:  00000000 00000000 00000000 00000000  
3ffffb30:  00000000 00000000 00000000 00000000  
3ffffb40:  00000000 00000000 00000000 00000000  
3ffffb50:  00000000 00000000 00000000 00000000  
3ffffb60:  00000000 00000000 00000000 00000000  
3ffffb70:  00000000 00000000 00000000 00000000  
3ffffb80:  00000000 00000000 00000000 00000000  
3ffffb90:  00000000 00000000 00000000 00000000  
3ffffba0:  00000000 00000000 00000000 00000000  
3ffffbb0:  00000000 00000000 00000000 00000000  
3ffffbc0:  00000000 00000000 00000000 00000000  
3ffffbd0:  00320000 00000000 3ffee92c 40208c0e  
3ffffbe0:  00000001 3fffff00 3fffff00 40208d29  
3ffffbf0:  00000000 00000000 3fffff00 3ffffe6c  
3ffffc00:  00000102 3ffee92c 3fffff00 4020920d  
3ffffc10:  00000000 00000000 00000000 00000000  
3ffffc20:  00000000 00000000 00000000 00000000  
3ffffc30:  00000000 00000000 00000000 00000000  
3ffffc40:  00000000 00000000 00000000 00000000  
3ffffc50:  00000000 00000000 00000000 00000000  
3ffffc60:  00000000 00000000 4023228b 00000001  
3ffffc70:  ffffffff 00000000 3ffe90a1 00000008  
3ffffc80:  402322da 3ffec6c0 3ffef1dc 00000001  
3ffffc90:  402323e6 3ffec6c0 3ffef1dc 3ffec6c0  
3ffffca0:  00000002 00000000 00000020 401013a6  
3ffffcb0:  3ffe8f52 40231397 3ffec6c0 3fff0a90  
3ffffcc0:  00000000 40224647 3ffedb78 00000000  
3ffffcd0:  00000000 00000002 00000001 3ffec6c0  
3ffffce0:  3fff0af6 40104e33 3fff0a90 3ffef5a4  
3ffffcf0:  3fff0ab4 00000000 00000000 00000000  
3ffffd00:  00000000 40216a31 3ffeeb74 3ffef5a4  
3ffffd10:  3fff0af6 0000007b 36310337 39310338  
3ffffd20:  6e690732 6464612d 72610472 00000000  
3ffffd30:  3ffeefcc 3ffeef94 3fff0ab4 40216cb3  
3ffffd40:  00000000 3ffeef94 3fff0ab4 402170c8  
3ffffd50:  3ffffd80 00000000 00000000 00000000  
3ffffd60:  00000000 00000000 00000020 401013a6  
3ffffd70:  3ffe8f50 40104790 3ffec800 4021e7f9  
3ffffd80:  00000005 00000000 00000020 401013a6  
3ffffd90:  3ffe8f55 401047ab 3ffec918 40102292  
3ffffda0:  00000005 00000000 00000020 401013a6  
3ffffdb0:  3ffe8f55 401047ab 3ffec918 40102292  
3ffffdc0:  401020c1 3ffec918 3ffed0d0 401013a6  
3ffffdd0:  00007fff 00dfa387 3ffed3ec 40102292  
3ffffde0:  3ffe97e8 00000000 00000000 00000001  
3ffffdf0:  00007fff 00dfa387 401026d2 00000100  
3ffffe00:  00000005 00000000 00000020 401013a6  
3ffffe10:  3ffe8f55 401047ab 3ffec918 00000022  
3ffffe20:  401020c1 3ffec918 00000000 4000050c  
3ffffe30:  00000000 00dfa5b5 3ffed3ec 40102292  
3ffffe40:  3ffe97f4 00000000 00000000 00000000  
3ffffe50:  00000000 00dfa5b5 401026d2 00000100  
3ffffe60:  7fffffff 3ffe97f4 3ffe97f4 00000001  
3ffffe70:  00000001 00006208 00000000 00000001  
3ffffe80:  ffffffff 00dfa5b5 00000000 4000050c  
3ffffe90:  3fffc278 4010246c 3fffc200 00000022  
3ffffea0:  3ffe9800 3fffc6fc 00000001 3ffeea8c  
3ffffeb0:  4020b535 00000030 0000001e ffffffff  
3ffffec0:  4020b524 00000001 4020b518 00000000  
3ffffed0:  00000000 00000000 00000000 fffffffe  
3ffffee0:  ffffffff 3fffc6fc 00000001 3ffeea8c  
3ffffef0:  00000000 3fffdad0 3ffeeac0 00000030  
3fffff00:  3ffeeb40 000002a3 000002a3 401005ac  
3fffff10:  3ffee92c 00000000 3fff05bc 401009f0  
3fffff20:  00000002 3fff03cc 3ffee92c 4021fdf0  
3fffff30:  4020bef8 00000000 4020bef8 00000000  
3fffff40:  00000001 3ffee92c 3fff0344 40206964  
3fffff50:  00000000 00000000 3ffee880 3ffeeac0  
3fffff60:  00000000 3ffee92c 3ffee880 3ffeeac0  
3fffff70:  3fffdad0 00000000 3ffee880 40204efc  
3fffff80:  003ff230 3ffee990 3ffee880 402038b6  
3fffff90:  00000000 00000000 00000001 4020b4ad  
3fffffa0:  3fffdad0 00000000 3ffeea8c 4020b53e  
<<<stack<<<

• Hardware: [ESP-12F]
• Development Env: [Arduino IDE]
• Operating System: [Windows]

Settings in IDE

• Module: [Generic ESP8266 Module]
• Flash Mode: [qio]
• Flash Size: [4MB]
• lwip Variant: [v2 Lower Memory]
• Reset Method: [nodemcu]
• Flash Frequency: [40Mhz]
• CPU Frequency: [80Mhz]
• Upload Using: [SERIAL]
• Upload Speed: [74880]

[earlephilhower]

@LaborEtArs, could you take a look here? Could this be due to a stack overflow or a callback that's not allowed while in SYS context?

[pfeerick]

For what it's worth, I'm running the current git version of the core on linux, and using the same settings bar serial speed - I had to change to 115200 as 74880 wasn't supported on my setup - I wasn't able to reproduce this. I had immediately prior run the ArduinoOTA sketch provided with the core with correct SSID and password, so did this with a full flash erase also, and it still didn't break (just OTA didn't work at all, as it didn't know what to connect to...).

Build date/time:         Jan 24 2019 / 19:46:45
Reset info:              Fatal exception:0 flag:6 (EXT_SYS_RST) epc1:0x00000000 epc2:0x00000000 epc3:0x00000000 excvaddr:0x00000000 depc:0x00000000
Boot mode:               1
Boot version:            31
Reset cause:             External System
CPU frequency (MHz):     80
Core version:            bff3a6d9
SDK version:             3.0.0-dev(c0f7b44)
Flash chip mode:         0
Flash size (by SDK):     4194304
Flash size (by chip ID): 4194304
Flash speed (MHz):       40
Sketch size/left:        309408 / 3862528
Sketch usage:            13%
Sketch MD5:              a7c3b1bdc443b9292ac487104d61bfd5
Free heap:               51536

start ota

[LaborEtArs]

Hmm, the stack trace is strange…
From the loop MDNSResponder::_process() is called (via…). The parameter is a bool, which would be ‘true’ here.
_process() hasn’t got any local vars, so the next entry in the stack trace should have been of ‘WiFi.isConnected(), MDNSResonder::_updateProbeStatus() or MDNSResponder::
_checkServiceQueryCache()’.
But it instead, we’re back at the loop_wrapper somehow…
Later (in the middle section), we’re back in the MDNSResponder where a mDNS answer is composed and transferred to the UDPContext. Again, this process isn’t completed… At the end it seems, that the ESP received data and the linked ‘MDNSResponder::_callProcess()’ is called, which would call ‘MDNSResponder::_process()’ next…

It seems, that the SYS context takes over, while the MDNSResponder is in the middle of processing a USER context job.
My understanding is, that control from USER to SYS mode is only transferred via yield, delay, … As there are no calls to these functions, I can’t see, why this should happen. Am I wrong here?

[devyte]

@LaborEtArs you are correct: context switch from CONT to SYS happens only on yield/delay and variants.

[earlephilhower]

Don't look too deeply in the stack dump, @LaborEtArs . There is no real stack unwinding on the 8266. What you're looking at is a reverse list of every int32_t on the stack that looks like an address. So some will be return addresses that were already used but not yet overwritten by another function which allocated lots of space but didn't overwrite that specific word. Or if some routines are using ints with a value in the pmem range, they'll be dumped, too.

The PC and EXECVADDR are golden, though.

I could be wrong, this is just looking quickly at it, but it seems like the "this" pointer for the MDNSResponder object or a method address was 0x40206977 which isn't possible (needs to be 4-byte aligned) unless an invalid pointer was coerced into an object pointer or (less likely) if there was memory corruption.

[LaborEtArs]

For a better understanding it would be helpful to have all the traces enabled. @milkpirate could you enable the traces. This could be done in ‚LEAmDNS_Priv.h‘; the out-commented line ‚#define DEBUG_ESP_MDNS_RESPONDER‘ needs to be enabled.

[milkpirate]

Sketch + DEBUG_ESP_MDNS_RESPONDER

#include <ArduinoOTA.h>
#include <ESP8266WiFi.h>
#include <Streaming.h>

void setup()
{
  Serial.begin(74880);
  delay(1);   // esp doesnt like writing to serial right away

  Serial<<endl<<endl;
  Serial<<F("Build date/time:         " __DATE__ " / " __TIME__)<<endl;
  Serial<<F("Reset info:              ")<<ESP.getResetInfo()<<endl;
  Serial<<F("Boot mode:               ")<<ESP.getBootMode()<<endl;
  Serial<<F("Boot version:            ")<<ESP.getBootVersion()<<endl;
  Serial<<F("Reset cause:             ")<<ESP.getResetReason()<<endl;
  Serial<<F("CPU frequency (MHz):     ")<<ESP.getCpuFreqMHz()<<endl;
  Serial<<F("Core version:            ")<<ESP.getCoreVersion()<<endl;
  
  Serial<<F("SDK version:             ")<<ESP.getSdkVersion()<<endl;
  Serial<<F("Flash chip mode:         ")<<ESP.getFlashChipMode()<<endl;
  Serial<<F("Flash size (by SDK):     ")<<ESP.getFlashChipSize()<<endl;
  Serial<<F("Flash size (by chip ID): ")<<ESP.getFlashChipRealSize()<< endl;
  Serial<<F("Flash speed (MHz):       ")<<ESP.getFlashChipSpeed()/1000000<<endl;
  
  Serial<<F("Sketch size/left:        ")<<ESP.getSketchSize()<<F(" / ") << ESP.getFreeSketchSpace()<<endl;
  Serial<<F("Sketch usage:            ")<<(ESP.getFreeSketchSpace()+ESP.getSketchSize())/ESP.getSketchSize()<<F("%")<<endl;
  Serial<<F("Sketch MD5:              ")<<ESP.getSketchMD5()<<endl;
  Serial<<F("Free heap:               ")<<ESP.getFreeHeap()<<endl; 

  WiFi.mode(WIFI_STA);
  WiFi.begin("ssid", "pass");

  Serial<<endl<<"start ota";
  
  ArduinoOTA.setHostname("espOTA");
  ArduinoOTA.begin();
}


void loop() {
  ArduinoOTA.handle();
}

Serial log (on power cycle)

 ets Jan  8 2013,rst cause:1, boot mode:(3,1)

load 0x4010f000, len 1384, room 16 
tail 8
chksum 0x2d
csum 0x2d
v0fd86a07
~ld


Build date/time:         Jan 24 2019 / 21:16:11
Reset info:              flag: 0
Boot mode:               1
Boot version:            31
Reset cause:             Power on
CPU frequency (MHz):     80
Core version:            2_5_0_BETA2
SDK version:             3.0.0-dev(c0f7b44)
Flash chip mode:         0
Flash size (by SDK):     4194304
Flash size (by chip ID): 4194304
Flash speed (MHz):       40
Sketch size/left:        371408 / 3821568
Sketch usage:            11%
Sketch MD5:              06dd8fff0048b02eeb61570895c2d7d9
Free heap:               48552

start ota[MDNSResponder] _sendMDNSMessage_Multicast: FAILED!
[MDNSResponder] _sendMDNSMessage: FAILED!
[MDNSResponder] _updateProbeStatus: FAILED!
... (a lot of them)
[MDNSResponder] _sendMDNSMessage_Multicast: FAILED!
[MDNSResponder] _sendMDNSMessage: FAILED!
[MDNSResponder] _updateProbeStatus: FAILED!

It stops plotting there and seems stable from that on. But a reset (via RST) makes it instable again.

Stack trace 1

Exception 0: Illegal instruction
PC: 0xbff76210
EXCVADDR: 0x00000000

Decoding stack results
0x40206fa3: esp8266::MDNSImplementation::MDNSResponder::_process(bool) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 74
0x40206fc4: esp8266::MDNSImplementation::MDNSResponder::_callProcess() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Helpers.cpp line 175
0x4020c5cb: std::_Function_handler    (esp8266::MDNSImplementation::MDNSResponder*)> >::_M_invoke(std::_Any_data const&) at c:\users\<user>\documents\arduinodata\packages\esp8266\tools\xtensa-lx106-elf-gcc\2.5.0-3-20ed2b9\xtensa-lx106-elf\include\c++\4.8.2/functional line 2073
0x40202e42: std::function ::operator()() const at c:\users\<user>\documents\arduinodata\packages\esp8266\tools\xtensa-lx106-elf-gcc\2.5.0-3-20ed2b9\xtensa-lx106-elf\include\c++\4.8.2/functional line 2465
0x40202e88: UdpContext::_s_recv(void*, udp_pcb*, pbuf*, ip4_addr const*, unsigned short) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266WiFi\src/include/UdpContext.h line 423
0x401002b0: pvPortMalloc at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\heap.c line 153
0x4021bbe4: udp_input at core/udp.c line 404
0x401007fc: malloc at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\umm_malloc\umm_malloc.c line 1673
0x40220000: autoip_start_probing at core/ipv4/autoip.c line 324
0x4021fcd8: ip4_input at core/ipv4/ip4.c line 704
0x401005ac: _umm_free at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\umm_malloc\umm_malloc.c line 1300
0x40217c59: ethernet_input_LWIP2 at netif/ethernet.c line 188
0x40217a8f: esp2glue_ethernet_input at glue-lwip/lwip-git.c line 422
0x4023705a: ethernet_input at glue-esp/lwip-esp.c line 363
0x4023706b: ethernet_input at glue-esp/lwip-esp.c line 371
0x40209048: esp8266::MDNSImplementation::MDNSResponder::_udpAppendBuffer(unsigned char const*, unsigned int) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1036
0x4020907a: esp8266::MDNSImplementation::MDNSResponder::_udpAppend8(unsigned char) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1048
0x40209621: esp8266::MDNSImplementation::MDNSResponder::_write8(unsigned char, esp8266::MDNSImplementation::MDNSResponder::stcMDNSSendParameter&) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1176
0x40209885: esp8266::MDNSImplementation::MDNSResponder::_writeMDNSHostDomain(char const*, bool, esp8266::MDNSImplementation::MDNSResponder::stcMDNSSendParameter&) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1289
0x402090ce: esp8266::MDNSImplementation::MDNSResponder::_udpAppend32(unsigned int) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1066
0x4020964d: esp8266::MDNSImplementation::MDNSResponder::_write16(unsigned short, esp8266::MDNSImplementation::MDNSResponder::stcMDNSSendParameter&) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1186
0x40209ba9: esp8266::MDNSImplementation::MDNSResponder::_writeMDNSAnswer_PTR_IP4(IPAddress, esp8266::MDNSImplementation::MDNSResponder::stcMDNSSendParameter&) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1421
0x40217649: glue2esp_linkoutput at glue-esp/lwip-esp.c line 299
0x40203891: ArduinoOTAClass::handle() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ArduinoOTA\ArduinoOTA.cpp line 365
0x40202928: loop() at C:\Users\<user>\AppData\Local\Temp\arduino_modified_sketch_232584/sketch_jan24a.ino line 42
0x4020c134: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 117
0x401009f0: free at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\umm_malloc\umm_malloc.c line 1760
0x40220a08: mem_free at core/mem.c line 237
0x40206f90: esp8266::MDNSImplementation::MDNSResponder::_process(bool) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 84
0x402051e8: esp8266::MDNSImplementation::MDNSResponder::update() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS.cpp line 1077
0x4020389a: ArduinoOTAClass::handle() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ArduinoOTA\ArduinoOTA.cpp line 366
0x4020c0c9: esp_schedule() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 95
0x4020c15a: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 127

Stack dump 1

Exception (0):
epc1=0xbff76210 epc2=0x00000000 epc3=0x00000000 excvaddr=0x00000000 depc=0x00000000

>>>stack>>>

ctx: sys
sp: 3fffec50 end: 3fffffb0 offset: 01a0
3fffedf0:  4022835d 00000000 3fffee80 00000000  
3fffee00:  00000000 00000000 00000000 00000000  
3fffee10:  00000000 00000000 00000000 4000050c  
3fffee20:  40224625 4010246c 3fffc200 00000022  
3fffee30:  00000000 3ffeea00 3fff04cc 40206fa3  
3fffee40:  3ffee330 3ffef2c4 00000000 40228ff3  
3fffee50:  00000000 01696b7f 4022905e 3fff0684  
3fffee60:  3fff06b6 00000000 3fff04cc 40206fc4  
3fffee70:  00000011 00000001 00000020 4020c5cb  
3fffee80:  00000000 10310606 00640100 40202e42  
3fffee90:  3fff06b6 00000000 3fff0514 40202e88  
3fffeea0:  00000052 401002b0 3fff0514 4021bbe4  
3fffeeb0:  000014e9 3ffef064 3ffef064 401007fc  
3fffeec0:  40220000 00000052 3fffef30 3ffef064  
3fffeed0:  3ffef10c 3fff0684 3fff06a2 4021fcd8  
3fffeee0:  00000014 00000000 3ffef064 401005ac  
3fffeef0:  3fffdc80 3ffef674 3fff02fc 3ffef6cc  
3fffef00:  00000008 3ffef064 3fff0684 40217c59  
3fffef10:  3fffdc80 3ffef674 3fff02fc 40217a8f  
3fffef20:  4023705a 3ffef674 3fff02fc 4023706b  
3fffef30:  3fff0694 3fff0684 00000002 3ffe85ec  
3fffef40:  40231d47 00000000 3fff02fc 40238cdf  
3fffef50:  40000f49 3fffdab0 3fffdab0 40000f49  
3fffef60:  40000e19 40001878 00000002 00000000  
3fffef70:  3fffff10 aa55aa55 000000ba 401048b4  
3fffef80:  401048ba 00000002 00000000 ea9c68fe  
3fffef90:  4010000d 7a50a683 fd451708 b94f2195  
3fffefa0:  00000000 3fffef3c 00000000 3fffff58  
3fffefb0:  3fffffc0 00000000 00000000 feefeffe  
3fffefc0:  feefeffe feefeffe feefeffe feefeffe  
...
3ffffa40:  feefeffe feefeffe feefeffe feefeffe  
3ffffa50:  00000001 feefeffe feefeffe feefeffe  
3ffffa60:  feefeffe feefeffe feefeffe 0000000c  
3ffffa70:  3ffef7bc 3ffeea00 00000001 40209048  
3ffffa80:  feefeffe feefeffe 3fffff00 4020907a  
3ffffa90:  feef020c feefeffe feefeffe feefeffe  
3ffffaa0:  feefeffe feefeffe 3fffff00 40209621  
3ffffab0:  feefeffe feefeffe 3fffff00 40209885  
3ffffac0:  00000000 00000000 00000000 00000000  
3ffffad0:  00000000 00000000 00000000 00000000  
3ffffae0:  00000000 00000000 00000000 00000000  
3ffffaf0:  00000000 00000000 00000000 00000000  
3ffffb00:  00000000 00000000 00000000 00000000  
3ffffb10:  00000000 00000000 00000000 00000000  
3ffffb20:  00000000 00000000 00000000 00000000  
3ffffb30:  00000000 00000000 00000000 00000000  
3ffffb40:  00000000 00000000 00000000 00000000  
3ffffb50:  00000000 00000000 00000000 00000000  
3ffffb60:  00000000 00000000 00000000 00000000  
3ffffb70:  00000000 00000000 00000000 00000000  
3ffffb80:  00000000 00000000 00000000 00000000  
3ffffb90:  00000000 00000000 00000000 00000000  
3ffffba0:  00000000 00000000 00000000 00000000  
3ffffbb0:  00000000 00000000 00000000 00000000  
3ffffbc0:  00000000 00000000 3ffeea00 402090ce  
3ffffbd0:  00000001 3fffff00 3fffff00 4020964d  
3ffffbe0:  00000000 00000000 3fffff00 3ffffe5c  
3ffffbf0:  00000102 3ffeea00 3fffff00 40209ba9  
3ffffc00:  00000000 00000000 00000000 00000000  
3ffffc10:  00000000 00000000 00000000 00000000  
3ffffc20:  00000000 00000000 00000000 00000000  
3ffffc30:  00000000 00000000 00000000 00000000  
3ffffc40:  00000000 00000000 00000000 00000000  
3ffffc50:  00000000 00000000 40232ea3 00000001  
3ffffc60:  ffffffff 00000000 3ffe9171 00000008  
3ffffc70:  40232ef2 3ffec790 3ffef2ac 00000001  
3ffffc80:  40232ffe 3ffec790 3ffef2ac 3ffec790  
3ffffc90:  00000002 00000000 00000020 401013a6  
3ffffca0:  3ffe9022 40231faf 3ffec790 3fff0bb0  
3ffffcb0:  00000000 4022525f 3ffedc48 00000000  
3ffffcc0:  00000000 00000002 00000001 3ffec790  
3ffffcd0:  3fff0c16 40104e33 3fff0bb0 3ffef674  
3ffffce0:  3fff0bd4 00000000 00000000 00000000  
3ffffcf0:  00000000 40217649 3ffeec44 3ffef674  
3ffffd00:  3fff0c16 0000007b 36310337 39310338  
3ffffd10:  6e690732 6464612d 72610472 00000000  
3ffffd20:  000005e0 00000000 401035b5 3ffed1a0  
3ffffd30:  0000003c 00000000 3fff0bd4 000000ff  
3ffffd40:  0000001c 00000001 401046f6 3ffed1a0  
3ffffd50:  3ffed170 00000000 00000000 3ffecdc4  
3ffffd60:  3ffec8d0 00000000 00000020 401013a6  
3ffffd70:  401042fb 3ffed1a0 3ffec9e8 3ffecdc4  
3ffffd80:  00000000 00000000 00000020 401013a6  
3ffffd90:  3ffe9020 40104790 3ffec8d0 40102292  
3ffffda0:  00000001 401039b3 3ffed1a0 00000000  
3ffffdb0:  40103e16 048355ba 3ffed4bc 40102292  
3ffffdc0:  401044c0 00080000 7fffffff 3ffed1a0  
3ffffdd0:  401038fa 00000027 7fffffff 00000000  
3ffffde0:  00000005 00000000 00000020 401013a6  
3ffffdf0:  3ffe9025 401047ab 3ffec9e8 4010508d  
3ffffe00:  401020c1 3ffec9e8 00000020 401013a6  
3ffffe10:  00000000 0484e5ba 3ffed4bc 40102292  
3ffffe20:  3ffe98b8 00000000 00000000 00000000  
3ffffe30:  00000000 0484e5ba 401026d2 00000100  
3ffffe40:  7fffffff 3ffe98b8 3ffe98b8 00000001  
3ffffe50:  00000001 00006208 401026d2 00000100  
3ffffe60:  7fffffff 0484e5ba 00000000 4000050c  
3ffffe70:  3fffc278 4010246c 3fffc200 00000022  
3ffffe80:  3ffe98c4 0484e38d 00000000 4000050c  
3ffffe90:  40203891 00000030 0000001e ffffffff  
3ffffea0:  40202928 00000001 4020c134 00000000  
3ffffeb0:  00000000 00000000 00000000 fffffffe  
3ffffec0:  ffffffff 3fffc6fc 00000001 3ffee950  
3ffffed0:  00000000 3fffdad0 3ffeeb90 00000030  
3ffffee0:  ffffffff 3fffc6fc 00000001 3ffeeb5c  
3ffffef0:  00000000 3fffdad0 3ffeeb90 00000030  
3fffff00:  00000000 3fffdad0 3ffeeb90 00000030  
3fffff10:  3ffeea00 00000000 3fff071c 401009f0  
3fffff20:  00000002 3fff0564 3ffeea00 40220a08  
3fffff30:  4020cb10 00000000 4020cb10 00000000  
3fffff40:  00000001 3ffeea00 3fff04cc 40206f90  
3fffff50:  00000000 00000000 3ffee950 3ffeeb90  
3fffff60:  00000000 3ffeea00 3ffee950 3ffeeb90  
3fffff70:  3fffdad0 00000000 3ffee950 402051e8  
3fffff80:  003ffad0 3ffee9e4 3ffee950 4020389a  
3fffff90:  00000000 00000000 00000001 4020c0c9  
3fffffa0:  3fffdad0 00000000 3ffeeb5c 4020c15a  
<<<stack<<<

Stack trace 2

Exception 0: Illegal instruction
PC: 0x40206400: esp8266::MDNSImplementation::MDNSResponder::_checkServiceQueryCache() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 1621
EXCVADDR: 0x00000000

Decoding stack results
0x40206012: esp8266::MDNSImplementation::MDNSResponder::_updateProbeStatus() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266/PolledTimeout.h line 92
0x40206f90: esp8266::MDNSImplementation::MDNSResponder::_process(bool) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 84
0x402051e8: esp8266::MDNSImplementation::MDNSResponder::update() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS.cpp line 1077
0x4020389a: ArduinoOTAClass::handle() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ArduinoOTA\ArduinoOTA.cpp line 366
0x40202928: loop() at C:\Users\<user>\AppData\Local\Temp\arduino_modified_sketch_232584/sketch_jan24a.ino line 42
0x4020c154: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 125

Stack dump 2

Exception (0):
epc1=0x40206400 epc2=0x00000000 epc3=0x00000000 excvaddr=0x00000000 depc=0x00000000

>>>stack>>>

ctx: cont
sp: 3ffffd70 end: 3fffffc0 offset: 01a0
3fffff10:  3ffeea00 3ffe8913 00000000 00000000  
3fffff20:  00000002 3fff0564 3ffeea00 40206012  
3fffff30:  4020cb10 00000000 4020cb10 00000000  
3fffff40:  00000001 3ffeea00 3fff04cc 40206f90  
3fffff50:  00000000 00000000 3ffee950 3ffeeb90  
3fffff60:  00000000 3ffeea00 3ffee950 3ffeeb90  
3fffff70:  3fffdad0 00000000 3ffee950 402051e8  
3fffff80:  003ffad0 3ffee9e4 3ffee950 4020389a  
3fffff90:  00000000 00000000 3ffeeb5c 40202928  
3fffffa0:  3fffdad0 00000000 3ffeeb5c 4020c154  
3fffffb0:  feefeffe feefeffe 3ffe85ec 40100a4d  
<<<stack<<<

Stack trace 3

Exception 9: LoadStoreAlignmentCause: Load or store to an unaligned address
PC: 0x40237dbf
EXCVADDR: 0x40104aeb

Decoding stack results
0x40206400: esp8266::MDNSImplementation::MDNSResponder::_checkServiceQueryCache() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 1621
0x40206f90: esp8266::MDNSImplementation::MDNSResponder::_process(bool) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 84
0x4020387d: ArduinoOTAClass::handle() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ArduinoOTA\ArduinoOTA.cpp line 358
0x40202928: loop() at C:\Users\<user>\AppData\Local\Temp\arduino_modified_sketch_613816/sketch_jan24a.ino line 42
0x4020c134: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 117
0x401005ac: _umm_free at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\umm_malloc\umm_malloc.c line 1300
0x401009f0: free at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\umm_malloc\umm_malloc.c line 1760
0x40220a08: mem_free at core/mem.c line 237
0x40206f90: esp8266::MDNSImplementation::MDNSResponder::_process(bool) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 84
0x402051e8: esp8266::MDNSImplementation::MDNSResponder::update() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS.cpp line 1077
0x4020389a: ArduinoOTAClass::handle() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ArduinoOTA\ArduinoOTA.cpp line 366
0x40202928: loop() at C:\Users\<user>\AppData\Local\Temp\arduino_modified_sketch_613816/sketch_jan24a.ino line 42
0x4020c154: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 125

Stack trace 4

Exception 9: LoadStoreAlignmentCause: Load or store to an unaligned address
PC: 0x40237dbf
EXCVADDR: 0x40104aeb

Decoding stack results
0x40206f90: esp8266::MDNSImplementation::MDNSResponder::_process(bool) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 84
0x4020c25c: run_scheduled_functions() at c:\users\<user>\documents\arduinodata\packages\esp8266\tools\xtensa-lx106-elf-gcc\2.5.0-3-20ed2b9\xtensa-lx106-elf\include\c++\4.8.2/functional line 2462
0x4020c157: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 126
0x40206058: esp8266::MDNSImplementation::MDNSResponder::_updateProbeStatus() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 1115
0x40206f90: esp8266::MDNSImplementation::MDNSResponder::_process(bool) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 84
0x402051e8: esp8266::MDNSImplementation::MDNSResponder::update() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS.cpp line 1077
0x4020389a: ArduinoOTAClass::handle() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ArduinoOTA\ArduinoOTA.cpp line 366
0x4020c157: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 126

[LaborEtArs]

@milkpirate : Thank for the additional logs. But I can’t see trace logs from the more verbose DEBUG_ESP_MDNS_INFO macros. Is this disabled in your code (a few line below the DEBUG_ESP_MDNS_RESPONDER definition)?
Have you also got the serial prints of the system before the crashes?
As @earlephilhower mentioned, the crash might be the result of a damaged stack, but currently I‘ve got no idea why this might happen...

[LaborEtArs]

@milkpirate BTW: You’re sketch is obviously not waiting for the WiFi to establish a connection (therefore the FAILED messages). Have you tried a sketch using the recommendated initialization process too?

[LaborEtArs]

Rethinking my last post, I think there might be the resolution hidden inside...
@earlephilhower @devyte : Would the WiFi callbacks (eg. onStationGotIP) be called in SYS mode? I‘d guess. So, in our case here, the callback will come as soon, as the IP is available (later than begin is called) and will call _restart() from SYS content...

[LaborEtArs]

@milkpirate : I did a setup with your code now, but (unfortunately !?) I can't reproduce your crashes. So we need to find the problem on your system/in your environment... If the problem is connected with an internal restart of the mDNS responder because WiFi establishes a connection only after MDNS::begin() is called (inside of OTA), then there should be two ways to solve this:
a: Wrap your WiFi.begin(xxx,xxx) into:
// Connect to WiFi network
WiFi.mode(WIFI_STA);
WiFi.begin(ssid, password);
Serial.println("");

// Wait for connection
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.print("Connected to ");
Serial.println(ssid);
Serial.print("IP address: ");
Serial.println(WiFi.localIP());

b: In file 'LEAmDNS.cpp', line 95 replace '_restart()' by 'schedule_function(std::bind(&MDNSResponder::_restart, this));'. And add the needed include for schedule_function '#include <Schedule.h>'

Even if the a. solution already solved the problem, I'd love to get the results of the b. solution in your environment too :-)

[milkpirate]

OK, sketch look like so:

#include <ArduinoOTA.h>
#include <ESP8266WiFi.h>
#include <Streaming.h>

void setup()
{
  Serial.begin(74880);
  delay(1);   // esp doesnt like writing to serial right away

  Serial<<endl<<endl;
  Serial<<F("Build date/time:         " __DATE__ " / " __TIME__)<<endl;
  Serial<<F("Reset info:              ")<<ESP.getResetInfo()<<endl;
  Serial<<F("Boot mode:               ")<<ESP.getBootMode()<<endl;
  Serial<<F("Boot version:            ")<<ESP.getBootVersion()<<endl;
  Serial<<F("Reset cause:             ")<<ESP.getResetReason()<<endl;
  Serial<<F("CPU frequency (MHz):     ")<<ESP.getCpuFreqMHz()<<endl;
  Serial<<F("Core version:            ")<<ESP.getCoreVersion()<<endl;
  
  Serial<<F("SDK version:             ")<<ESP.getSdkVersion()<<endl;
  Serial<<F("Flash chip mode:         ")<<ESP.getFlashChipMode()<<endl;
  Serial<<F("Flash size (by SDK):     ")<<ESP.getFlashChipSize()<<endl;
  Serial<<F("Flash size (by chip ID): ")<<ESP.getFlashChipRealSize()<< endl;
  Serial<<F("Flash speed (MHz):       ")<<ESP.getFlashChipSpeed()/1000000<<endl;
  
  Serial<<F("Sketch size/left:        ")<<ESP.getSketchSize()<<F(" / ") << ESP.getFreeSketchSpace()<<endl;
  Serial<<F("Sketch usage:            ")<<(ESP.getFreeSketchSpace()+ESP.getSketchSize())/ESP.getSketchSize()<<F("%")<<endl;
  Serial<<F("Sketch MD5:              ")<<ESP.getSketchMD5()<<endl;
  Serial<<F("Free heap:               ")<<ESP.getFreeHeap()<<endl; 

  WiFi.mode(WIFI_STA);
  WiFi.begin("ssid", "pass");

  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println();
  Serial.println("Connected!");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  Serial<<endl<<"start ota";
  
  ArduinoOTA.setHostname("espOTA");
  ArduinoOTA.begin();
}


void loop() {
  ArduinoOTA.handle();
}

LEAmDNS.cpp changes:

#include "LEAmDNS_Priv.h"
+#include <Schedule.h>

...

bool MDNSResponder::begin(const char* p_pcHostname) {
    
    bool    bResult = false;
    
    if (_setHostname(p_pcHostname)) {
        
        m_GotIPHandler = WiFi.onStationModeGotIP([this](const WiFiEventStationModeGotIP& pEvent) {
            (void) pEvent;
            _restart();
        });

        m_DisconnectedHandler = WiFi.onStationModeDisconnected([this](const WiFiEventStationModeDisconnected& pEvent) {
            (void) pEvent;
L96-            _restart();
L96+           schedule_function(std::bind(&MDNSResponder::_restart, this));
        });
            
        bResult = _restart();
    }
    DEBUG_EX_ERR(if (!bResult) { DEBUG_OUTPUT.printf_P(PSTR("[MDNSResponder] begin: FAILED for '%s'!\n"), (p_pcHostname ?: "-")); } );
    return bResult;
}

LEAmDNS_Priv.h changes:

// Enable class debug functions
#define ESP_8266_MDNS_INCLUDE
-//#define DEBUG_ESP_MDNS_RESPONDER
+#define DEBUG_ESP_MDNS_RESPONDER


#ifndef LWIP_OPEN_SRC
    #define LWIP_OPEN_SRC
#endif

// Enable/disable debug trace macros
#ifdef DEBUG_ESP_MDNS_RESPONDER
-//#define DEBUG_ESP_MDNS_INFO
+#define DEBUG_ESP_MDNS_INFO
#define DEBUG_ESP_MDNS_ERR
#define DEBUG_ESP_MDNS_TX
#define DEBUG_ESP_MDNS_RX
#endif

Serial:

Build date/time:         Jan 27 2019 / 16:26:28
Reset info:              Fatal exception:0 flag:6 (EXT_SYS_RST) epc1:0x00000000 epc2:0x00000000 epc3:0x00000000 excvaddr:0x00000000 depc:0x00000000
Boot mode:               1
Boot version:            31
Reset cause:             External System
CPU frequency (MHz):     80
Core version:            2_5_0_BETA2
SDK version:             3.0.0-dev(c0f7b44)
Flash chip mode:         0
Flash size (by SDK):     4194304
Flash size (by chip ID): 4194304
Flash speed (MHz):       40
Sketch size/left:        380096 / 3813376
Sketch usage:            11%
Sketch MD5:              aea10484ebd2ef555df3f63203e9ca40
Free heap:               48392
.
Connected!
IP address: 192.168.177.36

start ota[MDNSResponder] _allocUDPContext
[MDNSResponder] _updateProbeStatus: Starting host probing...
[MDNSResponder] _sendHostProbe (espOTA, 8830)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:1 AR:0
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent host probe
[MDNSResponder] _sendServiceProbe (espOTA.arduino.tcp, 8897)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:2 AR:2
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_PTR_NAME
[MDNSResponder] _writeMDNSAnswer_SRV
[MDNSResponder] _writeMDNSAnswer_TXT
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent service probe (1)
[MDNSResponder] _sendHostProbe (espOTA, 9115)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:1 AR:0
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent host probe
[MDNSResponder] _sendServiceProbe (espOTA.arduino.tcp, 9201)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:2 AR:2
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_PTR_NAME
[MDNSResponder] _writeMDNSAnswer_SRV
[MDNSResponder] _writeMDNSAnswer_TXT
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent service probe (2)
[MDNSResponder] _sendHostProbe (espOTA, 9400)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:1 AR:0
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent host probe
[MDNSResponder] _sendServiceProbe (espOTA.arduino.tcp, 9505)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:2 AR:2
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_PTR_NAME
[MDNSResponder] _writeMDNSAnswer_SRV
[MDNSResponder] _writeMDNSAnswer_TXT
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent service probe (3)
[MDNSResponder] _updateProbeStatus: Done host probing.
[MDNSResponder] _announce: Announcing host espOTA (3)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:1 OP:0 AA:1 TC:0 RD:0 RA:0 R:0 QD:0 AN:2 NS:0 AR:0
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _writeMDNSAnswer_PTR_IP4 (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Done service probing espOTA.arduino.tcp

Exception (0):
epc1=0x40203900 epc2=0x00000000 epc3=0x00000000 excvaddr=0x00000000 depc=0x00000000

>>>stack>>>

ctx: cont
sp: 3ffffdf0 end: 3fffffc0 offset: 01a0
3fffff90:  00000000 00000000 3ffeec10 4020298c  
3fffffa0:  3fffdad0 00000000 3ffeec10 4020d10c  
3fffffb0:  feefeffe feefeffe 3ffe85ec 40100a4d  
<<<stack<<<

Stack trace:

Exception 0: Illegal instruction
PC: 0x40203900: ArduinoOTAClass::handle() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ArduinoOTA\ArduinoOTA.cpp line 366
EXCVADDR: 0x00000000

Decoding stack results
0x4020298c: loop() at C:\Users\<user>\AppData\Local\Temp\arduino_modified_sketch_764153/sketch_jan27a.ino line 53
0x4020d10c: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 125

Serial dump 2:

Build date/time:         Jan 27 2019 / 16:26:28
Reset info:              Fatal exception:0 flag:2 (EXCEPTION) epc1:0x40203900 epc2:0x00000000 epc3:0x00000000 excvaddr:0x40104aeb depc:0x00000000
Boot mode:               1
Boot version:            31
Reset cause:             Exception
CPU frequency (MHz):     80
Core version:            2_5_0_BETA2
SDK version:             3.0.0-dev(c0f7b44)
Flash chip mode:         0
Flash size (by SDK):     4194304
Flash size (by chip ID): 4194304
Flash speed (MHz):       40
Sketch size/left:        380096 / 3813376
Sketch usage:            11%
Sketch MD5:              aea10484ebd2ef555df3f63203e9ca40
Free heap:               48392
.
Connected!
IP address: 192.168.177.36

start ota[MDNSResponder] _allocUDPContext
[MDNSResponder] _updateProbeStatus: Starting host probing...
[MDNSResponder] _parseMessage (Time: 859 ms, heap: 46624 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseMessage: Done (Succeeded after 1 ms, ate 0 bytes, remaining 46624)

[MDNSResponder] _parseMessage (Time: 871 ms, heap: 46600 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseMessage: Done (Succeeded after 14 ms, ate 0 bytes, remaining 46600)

[MDNSResponder] _sendHostProbe (espOTA, 948)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:1 AR:0
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent host probe
[MDNSResponder] _sendServiceProbe (espOTA.arduino.tcp, 1015)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:2 AR:2
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_PTR_NAME
[MDNSResponder] _writeMDNSAnswer_SRV
[MDNSResponder] _writeMDNSAnswer_TXT
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent service probe (1)
[MDNSResponder] _sendHostProbe (espOTA, 1233)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:1 AR:0
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent host probe
[MDNSResponder] _parseMessage (Time: 1269 ms, heap: 46432 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseResponse: Received a response
[MDNSResponder] _readRRAnswer
[MDNSResponder] _readRRAnswer: Reading 0x0001 answer (class:0x8001, TTL:10, RDLength:4) for <arduino-dev-host>-mshome-net.local
[MDNSResponder] _readRRAnswer: <arduino-dev-host>-mshome-net.local Type:0x0001 Class:0x0001 TTL:10, RDLength:4 A IP:172.28.157.97
[MDNSResponder] _processAnswers: Processing answers...
[MDNSResponder] _parseMessage: Done (Succeeded after 67 ms, ate 0 bytes, remaining 46432)

[MDNSResponder] _sendServiceProbe (espOTA.arduino.tcp, 1348)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:2 AR:2
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_PTR_NAME
[MDNSResponder] _writeMDNSAnswer_SRV
[MDNSResponder] _writeMDNSAnswer_TXT
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent service probe (2)
[MDNSResponder] _sendHostProbe (espOTA, 1518)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:1 AR:0
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent host probe
[MDNSResponder] _sendServiceProbe (espOTA.arduino.tcp, 1668)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:2 AR:2
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_PTR_NAME
[MDNSResponder] _writeMDNSAnswer_SRV
[MDNSResponder] _writeMDNSAnswer_TXT
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent service probe (3)
[MDNSResponder] _updateProbeStatus: Done host probing.
[MDNSResponder] _announce: Announcing host espOTA (3)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:1 OP:0 AA:1 TC:0 RD:0 RA:0 R:0 QD:0 AN:2 NS:0 AR:0
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _writeMDNSAnswer_PTR_IP4 (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Done service probing espOTA.arduino.tcp
[MDNSResponder] _parseMessage (Time: 1986 ms, heap: 46608 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseMessage: Done (Succeeded after 2 ms, ate 0 bytes, remaining 46608)

[MDNSResponder] _parseMessage (Time: 3008 ms, heap: 46616 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseMessage: Done (Succeeded after 1 ms, ate 0 bytes, remaining 46616)

[MDNSResponder] _parseMessage (Time: 5875 ms, heap: 46600 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseMessage: Done (Succeeded after 2 ms, ate 0 bytes, remaining 46600)

[MDNSResponder] _parseMessage (Time: 5887 ms, heap: 46624 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseMessage: Done (Succeeded after 15 ms, ate 0 bytes, remaining 46624)

[MDNSResponder] _parseMessage (Time: 6183 ms, heap: 46608 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseMessage: Done (Succeeded after 1 ms, ate 0 bytes, remaining 46608)

[MDNSResponder] _parseMessage (Time: 7004 ms, heap: 46608 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseMessage: Done (Succeeded after 1 ms, ate 0 bytes, remaining 46608)

[MDNSResponder] _parseMessage (Time: 8026 ms, heap: 46616 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseMessage: Done (Succeeded after 1 ms, ate 0 bytes, remaining 46616)


Exception (0):
epc1=0x40207921 epc2=0x00000000 epc3=0x00000000 excvaddr=0x40104aeb depc=0x00000000

>>>stack>>>

ctx: sys
sp: 3fffecd0 end: 3fffffb0 offset: 01a0
3fffee70:  4020d497 00000001 00000020 401013a6  
3fffee80:  00000000 10310606 00640100 40202ea6  
3fffee90:  3fff0c16 00000000 3fff0774 40202eec  
3fffeea0:  0000005b 401002b0 3fff0774 4021cb2c  
3fffeeb0:  000014e9 3ffef104 3ffef104 401007fc  
3fffeec0:  40220000 0000005b 3fffef30 3ffef104  
3fffeed0:  3ffef1ac 3fff0be4 3fff0c02 40220c20  
3fffeee0:  00000014 00000000 3ffef104 401005ac  
3fffeef0:  3fffdc80 3ffef714 3fff06b4 3ffef774  
3fffef00:  00000008 3ffef104 3fff0be4 40218ba1  
3fffef10:  3fffdc80 3ffef714 3fff06b4 402189d7  
3fffef20:  40237fa2 3ffef714 3fff06b4 40237fb3  
3fffef30:  3fff0bf4 3fff0be4 00000002 3ffe85ec  
3fffef40:  40232c8f 00000000 3fff06b4 40239c47  
3fffef50:  40000f49 3fffdab0 3fffdab0 40000f49  
3fffef60:  40000e19 40001878 00000002 3fffffc0  
3fffef70:  3fffff10 aa55aa55 000000ba 401048b4  
3fffef80:  401048ba 00000002 3fffffc0 ea9c68fe  
3fffef90:  4010000d 78502683 fd451708 b14f2195  
3fffefa0:  00000000 3fffef3c 00000000 3fffff58  
3fffefb0:  3fffffc0 00000000 00000000 feefeffe  
3fffefc0:  feefeffe feefeffe feefeffe feefeffe  
... 
3ffff8e0:  feefeffe feefeffe feefeffe feefeffe  
3ffff8f0:  feefeffe feefeffe feefeffe 00000000  
3ffff900:  3ffffa60 00000000 3ffffa60 4021554e  
3ffff910:  feefeffe 3ffffa03 feefeffe feefeffe  
3ffff920:  feefeffe feefeffe feefeffe 0000000e  
3ffff930:  3ffffa60 0000000e 3ffffa60 4021554e  
3ffff940:  feefeffe 3fff06ec 3ffff970 feefeffe  
3ffff950:  feefeffe feefeffe feefeffe 40215488  
3ffff960:  3ffffa60 3fff06ec 3ffff9c0 40211088  
3ffff970:  0000000e feefeffe feefeffe 00000002  
3ffff980:  00000000 00000002 3ffffa60 4021554e  
3ffff990:  feefeffe 4024898c feefeffe feefeffe  
3ffff9a0:  feefeffe feefeffe feefeffe 4024898c  
3ffff9b0:  00000000 4024898e 3ffffa60 40215738  
3ffff9c0:  00000000 0000000e 00000000 00000000  
3ffff9d0:  0000000e 0000003a fe302073 feefeffe  
3ffff9e0:  feefeffe feefeffe feefeffe feefeffe  
3ffff9f0:  feefeffe feefeffe feefeffe feefeffe  
3ffffa00:  00efeffe feefeffe feefeffe feefeffe  
3ffffa10:  feefeffe feefeffe 00000000 feefeffe  
3ffffa20:  00000001 3ffffb80 0000000c 3ffe8304  
3ffffa30:  0000000e 00000002 00000000 0000000c  
3ffffa40:  3fff03c4 3ffeea60 00000001 40209aec  
3ffffa50:  3ffeeb20 3ffe8304 3ffffef0 40209b1e  
3ffffa60:  3fff020c 00000025 00000005 ffff0208  
3ffffa70:  3ffffb30 0000003f 3ffffef0 4020a2e5  
3ffffa80:  feefeffe feefeffe 3ffffef0 4020a54c  
3ffffa90:  00000000 00000000 00000000 00000000  
3ffffaa0:  00000000 00000000 00000000 00000000  
3ffffab0:  00000000 00000000 00000000 00000000  
3ffffac0:  00000000 00000000 00000000 00000000  
3ffffad0:  00000000 00000000 00000000 00000000  
3ffffae0:  00000000 00000000 00000000 00000000  
3ffffaf0:  00000000 00000000 00000000 00000000  
3ffffb00:  00000000 00000000 00000000 00000000  
3ffffb10:  00000000 00000000 00000000 00000000  
3ffffb20:  00000000 00000000 00000000 00000000  
3ffffb30:  00000000 00000000 00000000 00000000  
3ffffb40:  00000000 00000000 00000000 00000000  
3ffffb50:  00000000 00000000 00000000 00000000  
3ffffb60:  00000000 00000000 00000000 00000000  
3ffffb70:  00000000 00000000 00000000 00000000  
3ffffb80:  00000000 00000000 00000000 00000000  
3ffffb90:  3ffe0000 3ffeea60 3ffeea60 40209b72  
3ffffba0:  00000001 3ffffef0 3ffffef0 4020a311  
3ffffbb0:  00000000 00000000 3ffffef0 3ffffe2c  
3ffffbc0:  00000102 3ffeea60 3ffffef0 4020a8f9  
3ffffbd0:  00000000 00000000 00000000 00000000  
3ffffbe0:  00000000 00000000 00000000 00000000  
3ffffbf0:  00000000 00000000 00000000 00000000  
3ffffc00:  00000000 00000000 00000000 00000000  
3ffffc10:  00000000 00000000 00000000 00000000  
3ffffc20:  00000000 00000000 00000000 00000000  
3ffffc30:  00000000 00000000 40233deb 00000001  
3ffffc40:  ffffffff 00000000 3ffe91d1 00000008  
3ffffc50:  40233e3a 3ffec818 3ffef34c 00000000  
3ffffc60:  3ffffdc0 00000000 3ffffdc0 4021554e  
3ffffc70:  00000002 3ffffd63 00000020 401013a6  
3ffffc80:  3ffe9082 40232ef7 3ffec818 00000003  
3ffffc90:  3ffffdc0 00000003 3ffffdc0 4021554e  
3ffffca0:  00000000 3fff07c4 3ffffcd0 3ffec818  
3ffffcb0:  3fff0b1e 40104e33 3fff088c 40215488  
3ffffcc0:  3ffffdc0 3fff07c4 3ffffd20 40211088  
3ffffcd0:  00000003 40218591 3ffeece8 00000001  
3ffffce0:  00000000 00000001 3ffffdc0 4021554e  
3ffffcf0:  00000000 402476c1 00000000 00000000  
3ffffd00:  3ffef13c 3ffef104 3fff0adc 402476c1  
3ffffd10:  00000000 402476c2 3ffffdc0 40215738  
3ffffd20:  00000000 00000003 00000000 00000000  
3ffffd30:  00000003 0000004c 3f302073 3fff0adc  
3ffffd40:  00000001 401039b3 3ffed248 40220359  
3ffffd50:  00000005 00000000 00000020 401013a6  
3ffffd60:  3ffe9085 401047ab 3ffeca48 40220e48  
3ffffd70:  401020c1 3ffeca48 00000000 00000002  
3ffffd80:  00000005 00000000 00000020 401013a6  
3ffffd90:  3ffe9085 401047ab 3ffeca48 00000000  
3ffffda0:  00000005 00000000 00000020 401013a6  
3ffffdb0:  3ffe9085 401047ab 3ffeca48 40102292  
3ffffdc0:  401020c1 3ffeca48 00000000 401013a6  
3ffffdd0:  00007fff 00a30fee 3ffed51c 40102292  
3ffffde0:  00000005 00000000 00000020 401013a6  
3ffffdf0:  3ffe9085 401047ab 3ffeca48 00000100  
3ffffe00:  401020c1 3ffeca48 3ffe9924 00000001  
3ffffe10:  00000001 00a6321d 3ffed51c 40102292  
3ffffe20:  3ffe9900 00000000 00000000 4000050c  
3ffffe30:  00000001 00a6321d 401026d2 00000100  
3ffffe40:  7fffffff 3ffe9900 3ffe9900 00000001  
3ffffe50:  00000001 00006208 00000000 fffffffe  
3ffffe60:  ffffffff 00a6321d 00000000 4000050c  
3ffffe70:  3fffc278 4010246c 3fffc200 00000022  
3ffffe80:  3ffe990c 3fffc6fc 00000001 3fff072c  
3ffffe90:  402038fb 00000030 0000001e ffffffff  
3ffffea0:  4020298c 3ffeea60 4020d0ec 00000000  
3ffffeb0:  00000000 00000000 00000000 fffffffe  
3ffffec0:  ffffffff 3fffc6fc 00000001 3ffee9b0  
3ffffed0:  00000000 3fffdad0 3ffeec44 00000030  
3ffffee0:  ffffffff 3fffc6fc 00000001 3ffeec10  
3ffffef0:  00000000 3fffdad0 3ffeec44 00000030  
3fffff00:  00000000 3fffdad0 3ffeec44 00000030  
3fffff10:  3ffeea60 00000000 3fff09ec 401009f0  
3fffff20:  00000002 3fff08cc 3ffeea60 40221950  
3fffff30:  4020da58 00000000 4020da58 00000000  
3fffff40:  00000001 3ffeea60 3fff072c 402078f0  
3fffff50:  00000000 00000000 3ffee9b0 3ffeec44  
3fffff60:  00000000 3ffeea60 3ffee9b0 3ffeec44  
3fffff70:  3fffdad0 00000000 3ffee9b0 40205324  
3fffff80:  003ffcc0 3ffeea44 3ffee9b0 402038fe  
3fffff90:  00000000 00000000 00000001 4020d081  
3fffffa0:  3fffdad0 00000000 3ffeec10 4020d112  
<<<stack<<<

Stack trace 2:

Exception 0: Illegal instruction
PC: 0x40207921: esp8266::MDNSImplementation::MDNSResponder::_callProcess() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Helpers.cpp line 174
EXCVADDR: 0x40104aeb

Decoding stack results
0x4020d497: std::_Function_handler    (esp8266::MDNSImplementation::MDNSResponder*)> >::_M_invoke(std::_Any_data const&) at c:\users\<user>\documents\arduinodata\packages\esp8266\tools\xtensa-lx106-elf-gcc\2.5.0-3-20ed2b9\xtensa-lx106-elf\include\c++\4.8.2/functional line 2073
0x40202ea6: std::function ::operator()() const at c:\users\<user>\documents\arduinodata\packages\esp8266\tools\xtensa-lx106-elf-gcc\2.5.0-3-20ed2b9\xtensa-lx106-elf\include\c++\4.8.2/functional line 2465
0x40202eec: UdpContext::_s_recv(void*, udp_pcb*, pbuf*, ip4_addr const*, unsigned short) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266WiFi\src/include/UdpContext.h line 423
0x401002b0: pvPortMalloc at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\heap.c line 153
0x4021cb2c: udp_input at core/udp.c line 404
0x401007fc: malloc at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\umm_malloc\umm_malloc.c line 1673
0x40220000: etharp_request at core/ipv4/etharp.c line 1183
0x40220c20: ip4_input at core/ipv4/ip4.c line 704
0x401005ac: _umm_free at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\umm_malloc\umm_malloc.c line 1300
0x40218ba1: ethernet_input_LWIP2 at netif/ethernet.c line 188
0x402189d7: esp2glue_ethernet_input at glue-lwip/lwip-git.c line 422
0x40237fa2: ethernet_input at glue-esp/lwip-esp.c line 363
0x40237fb3: ethernet_input at glue-esp/lwip-esp.c line 371
0x4021554e: __ssputs_r at ../../../../../../dl/newlib-xtensa/newlib/libc/stdio/nano-vfprintf.c line 233
0x4021554e: __ssputs_r at ../../../../../../dl/newlib-xtensa/newlib/libc/stdio/nano-vfprintf.c line 233
0x40215488: __ssputs_r at ../../../../../../dl/newlib-xtensa/newlib/libc/stdio/nano-vfprintf.c line 180
0x40211088: _printf_i at ../../../../../../dl/newlib-xtensa/newlib/libc/stdio/nano-vfprintf_i.c line 244
0x4021554e: __ssputs_r at ../../../../../../dl/newlib-xtensa/newlib/libc/stdio/nano-vfprintf.c line 233
0x40215738: _svfprintf_r at ../../../../../../dl/newlib-xtensa/newlib/libc/stdio/nano-vfprintf.c line 531
0x40209aec: esp8266::MDNSImplementation::MDNSResponder::_udpAppendBuffer(unsigned char const*, unsigned int) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1036
0x40209b1e: esp8266::MDNSImplementation::MDNSResponder::_udpAppend8(unsigned char) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1048
0x4020a2e5: esp8266::MDNSImplementation::MDNSResponder::_write8(unsigned char, esp8266::MDNSImplementation::MDNSResponder::stcMDNSSendParameter&) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1176
0x4020a54c: esp8266::MDNSImplementation::MDNSResponder::_writeMDNSHostDomain(char const*, bool, esp8266::MDNSImplementation::MDNSResponder::stcMDNSSendParameter&) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1289
0x40209b72: esp8266::MDNSImplementation::MDNSResponder::_udpAppend32(unsigned int) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1066
0x4020a311: esp8266::MDNSImplementation::MDNSResponder::_write16(unsigned short, esp8266::MDNSImplementation::MDNSResponder::stcMDNSSendParameter&) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1186
0x4020a8f9: esp8266::MDNSImplementation::MDNSResponder::_writeMDNSAnswer_PTR_IP4(IPAddress, esp8266::MDNSImplementation::MDNSResponder::stcMDNSSendParameter&) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Transfer.cpp line 1421
0x4021554e: __ssputs_r at ../../../../../../dl/newlib-xtensa/newlib/libc/stdio/nano-vfprintf.c line 233
0x4021554e: __ssputs_r at ../../../../../../dl/newlib-xtensa/newlib/libc/stdio/nano-vfprintf.c line 233
0x40215488: __ssputs_r at ../../../../../../dl/newlib-xtensa/newlib/libc/stdio/nano-vfprintf.c line 180
0x40211088: _printf_i at ../../../../../../dl/newlib-xtensa/newlib/libc/stdio/nano-vfprintf_i.c line 244
0x40218591: glue2esp_linkoutput at glue-esp/lwip-esp.c line 299
0x4021554e: __ssputs_r at ../../../../../../dl/newlib-xtensa/newlib/libc/stdio/nano-vfprintf.c line 233
0x40215738: _svfprintf_r at ../../../../../../dl/newlib-xtensa/newlib/libc/stdio/nano-vfprintf.c line 531
0x40220359: etharp_output_LWIP2 at core/ipv4/etharp.c line 896
0x40220e48: ip4_output_if_opt_src at core/ipv4/ip4.c line 1007
0x402038fb: ArduinoOTAClass::handle() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ArduinoOTA\ArduinoOTA.cpp line 365
0x4020298c: loop() at C:\Users\<user>\AppData\Local\Temp\arduino_modified_sketch_764153/sketch_jan27a.ino line 53
0x4020d0ec: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 117
0x401009f0: free at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\umm_malloc\umm_malloc.c line 1760
0x40221950: mem_free at core/mem.c line 237
0x402078f0: esp8266::MDNSImplementation::MDNSResponder::_process(bool) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 84
0x40205324: esp8266::MDNSImplementation::MDNSResponder::update() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS.cpp line 1078
0x402038fe: ArduinoOTAClass::handle() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ArduinoOTA\ArduinoOTA.cpp line 366
0x4020d081: esp_schedule() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 95
0x4020d112: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 127

Serial dump 3:

Build date/time:         Jan 27 2019 / 16:26:28
Reset info:              Fatal exception:0 flag:4 (SOFT_RESTART) epc1:0x00000000 epc2:0x00000000 epc3:0x00000000 excvaddr:0x00000000 depc:0x00000000
Boot mode:               1
Boot version:            31
Reset cause:             Software/System restart
CPU frequency (MHz):     80
Core version:            2_5_0_BETA2
SDK version:             3.0.0-dev(c0f7b44)
Flash chip mode:         0
Flash size (by SDK):     4194304
Flash size (by chip ID): 4194304
Flash speed (MHz):       40
Sketch size/left:        380096 / 3813376
Sketch usage:            11%
Sketch MD5:              aea10484ebd2ef555df3f63203e9ca40
Free heap:               48392
.
Connected!
IP address: 192.168.177.36

start ota[MDNSResponder] _allocUDPContext
[MDNSResponder] _updateProbeStatus: Starting host probing...
[MDNSResponder] _parseMessage (Time: 874 ms, heap: 46624 bytes, from 192.168.177.1(5353), to 224.0.0.251(5353))
[MDNSResponder] _readRRQuestion
[MDNSResponder] _readRRQuestion <arduino-dev-host>-mshome-net.local Type:0x0001 Class:0x0001 Multicast
[MDNSResponder] _replyMaskForHost: 0
[MDNSResponder] _replyMaskForService(espOTA.arduino.tcp): 0
[MDNSResponder] _parseMessage: Done (Succeeded after 30 ms, ate 0 bytes, remaining 46624)

[MDNSResponder] _parseMessage (Time: 917 ms, heap: 46552 bytes, from 192.168.177.1(5353), to 224.0.0.251(5353))
[MDNSResponder] _readRRQuestion
[MDNSResponder] _readRRQuestion <arduino-dev-host>-mshome-net.local Type:0x00FF Class:0x0001 Multicast
[MDNSResponder] _replyMaskForHost: 0
[MDNSResponder] _replyMaskForService(espOTA.arduino.tcp): 0
[MDNSResponder] _parseMessage: Done (Succeeded after 45 ms, ate 0 bytes, remaining 46552)

[MDNSResponder] _parseMessage (Time: 975 ms, heap: 46640 bytes, from 192.168.177.1(5353), to 224.0.0.251(5353))
[MDNSResponder] _readRRQuestion
[MDNSResponder] _readRRQuestion espOTA.local Type:0x00FF Class:0x0001 Multicast
[MDNSResponder] _replyMaskForHost: 1
[MDNSResponder] _parseQuery: Possible race-condition for host domain detected while probing.
[MDNSResponder] _parseQuery: Possible race-condition for host domain detected while probing.
[MDNSResponder] _replyMaskForService(espOTA.arduino.tcp): 0
[MDNSResponder] _parseQuery: UNSOLVED tiebreak-need for host domain!
[MDNSResponder] _parseMessage: Done (Succeeded after 76 ms, ate 0 bytes, remaining 46640)

[MDNSResponder] _sendHostProbe (espOTA, 1064)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:1 AR:0
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent host probe
[MDNSResponder] _sendServiceProbe (espOTA.arduino.tcp, 1115)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:2 AR:2
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_PTR_NAME
[MDNSResponder] _writeMDNSAnswer_SRV
[MDNSResponder] _writeMDNSAnswer_TXT
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent service probe (1)
[MDNSResponder] _parseMessage (Time: 1188 ms, heap: 46064 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseResponse: Received a response
[MDNSResponder] _readRRAnswer
[MDNSResponder] _readRRAnswer: Reading 0x0001 answer (class:0x8001, TTL:9, RDLength:4) for <arduino-dev-host-router>.local
[MDNSResponder] _readRRAnswer: <arduino-dev-host-router>.local Type:0x0001 Class:0x0001 TTL:9, RDLength:4 A IP:192.168.177.23
[MDNSResponder] _processAnswers: Processing answers...
[MDNSResponder] _parseMessage: Done (Succeeded after 65 ms, ate 0 bytes, remaining 46064)

[MDNSResponder] _sendHostProbe (espOTA, 1365)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:1 AR:0
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent host probe
[MDNSResponder] _sendServiceProbe (espOTA.arduino.tcp, 1436)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:2 AR:2
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_PTR_NAME
[MDNSResponder] _writeMDNSAnswer_SRV
[MDNSResponder] _writeMDNSAnswer_TXT
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent service probe (2)
[MDNSResponder] _sendHostProbe (espOTA, 1650)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:1 AR:0
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent host probe
[MDNSResponder] _sendServiceProbe (espOTA.arduino.tcp, 1740)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:0 OP:0 AA:0 TC:0 RD:0 RA:0 R:0 QD:1 AN:0 NS:2 AR:2
[MDNSResponder] _writeMDNSQuestion
[MDNSResponder] _writeMDNSAnswer_PTR_NAME
[MDNSResponder] _writeMDNSAnswer_SRV
[MDNSResponder] _writeMDNSAnswer_TXT
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Did sent service probe (3)
[MDNSResponder] _updateProbeStatus: Done host probing.
[MDNSResponder] _announce: Announcing host espOTA (3)
[MDNSResponder] _sendMDNSMessage_Multicast: Will send to '224.0.0.251'.
[MDNSResponder] _prepareMDNSMessage
[MDNSResponder] _prepareMDNSMessage: ID:0 QR:1 OP:0 AA:1 TC:0 RD:0 RA:0 R:0 QD:0 AN:2 NS:0 AR:0
[MDNSResponder] _writeMDNSAnswer_A (192.168.177.36)
[MDNSResponder] _writeMDNSAnswer_PTR_IP4 (192.168.177.36)
[MDNSResponder] _updateProbeStatus: Done service probing espOTA.arduino.tcp
[MDNSResponder] _parseMessage (Time: 3126 ms, heap: 46624 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseMessage: Done (Succeeded after 1 ms, ate 0 bytes, remaining 46624)

[MDNSResponder] _parseMessage (Time: 3137 ms, heap: 46600 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseMessage: Done (Succeeded after 15 ms, ate 0 bytes, remaining 46600)

[MDNSResponder] _parseMessage (Time: 3433 ms, heap: 46608 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseMessage: Done (Succeeded after 1 ms, ate 0 bytes, remaining 46608)

[MDNSResponder] _parseMessage (Time: 4152 ms, heap: 46608 bytes, from 192.168.177.23(5353), to 224.0.0.251(5353))
[MDNSResponder] _parseMessage: Done (Succeeded after 1 ms, ate 0 bytes, remaining 46608)


Exception (9):
epc1=0x40238d1f epc2=0x00000000 epc3=0x00000000 excvaddr=0x40104aeb depc=0x00000000

>>>stack>>>

ctx: cont
sp: 3ffffca0 end: 3fffffc0 offset: 01a0
3ffffe40:  00000022 401036f6 00040000 00000001  
3ffffe50:  3ffed200 40102616 0000001b 40104aeb  
3ffffe60:  40104acc 3fffc100 3fffdad0 00000000  
3ffffe70:  40104ae5 40104ae2 3fffc200 00000022  
3ffffe80:  400005e1 3fffc6fc 00000001 3fff072c  
3ffffe90:  40203900 00000030 0000001e ffffffff  
3ffffea0:  4020298c 00000001 00000001 00000000  
3ffffeb0:  00000000 00000000 00000000 fffffffe  
3ffffec0:  ffffffff 3fffc6fc 00000001 3ffee9b0  
3ffffed0:  00000000 3fffdad0 3ffeec44 00000000  
3ffffee0:  00000000 00000000 00000000 fffffffe  
3ffffef0:  ffffffff 3fffc6fc 00000001 3ffe85ec  
3fffff00:  00000000 3fffdad0 3ffeec44 00000030  
3fffff10:  3ffeea60 00000000 3fff09ec 401009f0  
3fffff20:  00000002 3fff08cc 3ffeea60 40221950  
3fffff30:  4020da58 00000000 4020da58 00000000  
3fffff40:  00000001 3ffeea60 3fff072c 402078f0  
3fffff50:  00000000 00000000 3ffee9b0 3ffeec44  
3fffff60:  00000000 3ffeea60 3ffee9b0 3ffeec44  
3fffff70:  3fffdad0 00000000 3ffee9b0 40205324  
3fffff80:  003ffcc0 3ffeea44 3ffee9b0 402038fe  
3fffff90:  00000000 00000000 3ffeec10 4020298c  
3fffffa0:  3fffdad0 00000000 3ffeec10 4020d10c  
3fffffb0:  feefeffe feefeffe 3ffe85ec 40100a4d  
<<<stack<<<

Stack trace 3

Exception 9: LoadStoreAlignmentCause: Load or store to an unaligned address
PC: 0x40238d1f
EXCVADDR: 0x40104aeb

Decoding stack results
0x40203900: ArduinoOTAClass::handle() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ArduinoOTA\ArduinoOTA.cpp line 366
0x4020298c: loop() at C:\Users\<user>\AppData\Local\Temp\arduino_modified_sketch_764153/sketch_jan27a.ino line 53
0x401009f0: free at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\umm_malloc\umm_malloc.c line 1760
0x40221950: mem_free at core/mem.c line 237
0x402078f0: esp8266::MDNSImplementation::MDNSResponder::_process(bool) at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS_Control.cpp line 84
0x40205324: esp8266::MDNSImplementation::MDNSResponder::update() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ESP8266mDNS\src\LEAmDNS.cpp line 1078
0x402038fe: ArduinoOTAClass::handle() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\libraries\ArduinoOTA\ArduinoOTA.cpp line 366
0x4020298c: loop() at C:\Users\<user>\AppData\Local\Temp\arduino_modified_sketch_764153/sketch_jan27a.ino line 53
0x4020d10c: loop_wrapper() at C:\Users\<user>\Documents\ArduinoData\packages\esp8266\hardware\esp8266\2.5.0-beta2\cores\esp8266\core_esp8266_main.cpp line 125

[LaborEtArs]

Again many thanks for the logs!
Unfortunately you hit the wrong callback (maybe my fault, because line numbers can vary...). The change should have gone to the 'WiFi.onStationModeGotIP' callback...
However, as your code is waiting for the connection now, a hidden call to 'LEAmDNSResponder::_restart()' after the IP is assigned can't be the reason of the crashes anymore.
As I can't reproduce the crash here, I'm currently out of ideas. Maybe you should switch back to the old mDNS responder for a while. This could be done in 'ESP8266MDNS.h'. Enable the code in line 51 instead of line 52.

[milkpirate]

:/ so not hope? would fire the IDE with whatever you tell me to...