nfty: aiodns.error.DNSError Timeout while contacting DNS servers

[acidicX]

The problem

Since 2025.10.0, I'm getting DNS Errors with my own server.

I have checked that everything is reachable from inside the home assistant container, dig also returns the correct IP. So my DNS setup works.

What version of Home Assistant Core has the issue?

core-2025.10.1

What was the last working version of Home Assistant Core?

core-2025.09.something

What type of installation are you running?

Home Assistant Container

Integration causing the issue

ntfy

Link to integration documentation on our website

https://www.home-assistant.io/integrations/ntfy

Diagnostics information

No response

Example YAML snippet

Anything in the logs that might be useful for us?

2025-10-04 17:49:25.953 DEBUG (MainThread) [homeassistant.components.ntfy] Error
Traceback (most recent call last):
  File "/usr/local/lib/python3.13/site-packages/aiohttp/resolver.py", line 117, in resolve
    resp = await self._resolver.getaddrinfo(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ...<5 lines>...
    )
    ^
aiodns.error.DNSError: (12, 'Timeout while contacting DNS servers')

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/lib/python3.13/site-packages/aiohttp/connector.py", line 1532, in _create_direct_connection
    hosts = await self._resolve_host(host, port, traces=traces)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/aiohttp/connector.py", line 1148, in _resolve_host
    return await asyncio.shield(resolved_host_task)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/aiohttp/connector.py", line 1179, in _resolve_host_with_throttle
    addrs = await self._resolver.resolve(host, port, family=self._family)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/aiohttp_asyncmdnsresolver/_impl.py", line 140, in resolve
    return await super().resolve(host, port, family)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/aiohttp/resolver.py", line 126, in resolve
    raise OSError(None, msg) from exc
OSError: [Errno None] Timeout while contacting DNS servers

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/lib/python3.13/site-packages/aiontfy/ntfy.py", line 89, in _request
    async with self._session.request(method, url, **kwargs) as r:
               ~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/aiohttp/client.py", line 1488, in __aenter__
    self._resp: _RetType = await self._coro
                           ^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/aiohttp/client.py", line 770, in _request
    resp = await handler(req)
           ^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/aiohttp/client.py", line 725, in _connect_and_send_request
    conn = await self._connector.connect(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        req, traces=traces, timeout=real_timeout
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/usr/local/lib/python3.13/site-packages/aiohttp/connector.py", line 642, in connect
    proto = await self._create_connection(req, traces, timeout)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/aiohttp/connector.py", line 1209, in _create_connection
    _, proto = await self._create_direct_connection(req, traces, timeout)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/aiohttp/connector.py", line 1538, in _create_direct_connection
    raise ClientConnectorDNSError(req.connection_key, exc) from exc
aiohttp.client_exceptions.ClientConnectorDNSError: Cannot connect to host ntfy.myhost.url:443 ssl:default [Timeout while contacting DNS servers]

Additional information

No response

[home-assistant]

Hey there @tr4nt0r, mind taking a look at this issue as it has been labeled with an integration (ntfy) you are listed as a code owner for? Thanks!

Code owner commands

Code owners of ntfy can trigger bot actions by commenting:

• @home-assistant close Closes the issue.
• @home-assistant rename Awesome new title Renames the issue.
• @home-assistant reopen Reopen the issue.
• @home-assistant unassign ntfy Removes the current integration label and assignees on the issue, add the integration domain after the command.
• @home-assistant add-label needs-more-information Add a label (needs-more-information, problem in dependency, problem in custom component) to the issue.
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---

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[tr4nt0r]

is ntfy.myhost.url:443 really the correct URL?

[acidicX]

@tr4nt0r no I redacted it, but it's valid (I haven't entered it with :443 though)

[acidicX]

There also seems to be other addons with that issue, maybe aiodns uses a DNS server that is rate limiting or something?
#150862

ntfy is the only integration with issues in my setup though, and it only started with 2025.10 - but as it is a network service, might also be unrelated to the version

[acidicX]

I just checked it and now the addon is in available state again.. might really be rate limiting on whatever aiodns uses? Maybe too many requests while HA is starting?

[tr4nt0r]

it did not time out while contacting the ntfy instance, it timed out while contacting your DNS server

[acidicX]

Are you sure it uses the locally configured DNS server and not another one? Because I used dig inside the container to query the configured DNS server with the domain, and it returned a result without issues... at the same time that the integration failed

[tr4nt0r]

the integration is using the http client session provided by Home Assistant, so that's a bit weird. What changed in the ntfy integration are the event entities that subscribe to the topics by websocket. Could you try if you deactivate all event entities first?

[acidicX]

@tr4nt0r sure, just did. Same issues, sadly. After HA restart, the error is always the same.
If I only reload the integration once it is in a working state, there are no errors. Really weird behavior.

[acidicX]

After the 2nd restart with deactivated entities if did work instantly 🤔
But maybe the result is cached somehow? I'll try again in a few hours

[acidicX]

this might be the solution to the problem: rnovacek/homeassistant_cz_energy_spot_prices#104 (comment)

[acidicX]

@tr4nt0r still getting the issues. Were you able to check the linked post for a solution?

[acidicX]

@tr4nt0r with the upgrade to HA 2025.11.2, it seems to have switched from DNS timeout to full blown not able to connect again.

 2025-11-18 21:28:29.914 DEBUG (MainThread) [homeassistant.components.ntfy] Error
 Traceback (most recent call last):
   File "/usr/local/lib/python3.13/site-packages/aiohttp/connector.py", line 1268, in _wrap_create_connection
     sock = await aiohappyeyeballs.start_connection(
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     ...<6 lines>...
     )
     ^
   File "/usr/local/lib/python3.13/site-packages/aiohappyeyeballs/impl.py", line 122, in start_connection
     raise first_exception
   File "/usr/local/lib/python3.13/site-packages/aiohappyeyeballs/impl.py", line 73, in start_connection
     sock = await _connect_sock(
            ^^^^^^^^^^^^^^^^^^^^
     ...<6 lines>...
     )
     ^
   File "/usr/local/lib/python3.13/site-packages/aiohappyeyeballs/impl.py", line 208, in _connect_sock
     await loop.sock_connect(sock, address)
   File "/usr/local/lib/python3.13/asyncio/selector_events.py", line 641, in sock_connect
     return await fut
            ^^^^^^^^^
   File "/usr/local/lib/python3.13/asyncio/selector_events.py", line 649, in _sock_connect
     sock.connect(address)
     ~~~~~~~~~~~~^^^^^^^^^
 OSError: [Errno 101] Network unreachable
 
 The above exception was the direct cause of the following exception:
 
 Traceback (most recent call last):
   File "/usr/local/lib/python3.13/site-packages/aiontfy/ntfy.py", line 89, in _request
     async with self._session.request(method, url, **kwargs) as r:
                ~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
   File "/usr/local/lib/python3.13/site-packages/aiohttp/client.py", line 1510, in __aenter__
     self._resp: _RetType = await self._coro
                            ^^^^^^^^^^^^^^^^
   File "/usr/local/lib/python3.13/site-packages/aiohttp/client.py", line 779, in _request
     resp = await handler(req)
            ^^^^^^^^^^^^^^^^^^
   File "/usr/local/lib/python3.13/site-packages/aiohttp/client.py", line 734, in _connect_and_send_request
     conn = await self._connector.connect(
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
         req, traces=traces, timeout=real_timeout
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     )
     ^
   File "/usr/local/lib/python3.13/site-packages/aiohttp/connector.py", line 642, in connect
     proto = await self._create_connection(req, traces, timeout)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   File "/usr/local/lib/python3.13/site-packages/aiohttp/connector.py", line 1209, in _create_connection
     _, proto = await self._create_direct_connection(req, traces, timeout)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   File "/usr/local/lib/python3.13/site-packages/aiohttp/connector.py", line 1581, in _create_direct_connection
     raise last_exc
   File "/usr/local/lib/python3.13/site-packages/aiohttp/connector.py", line 1550, in _create_direct_connection
     transp, proto = await self._wrap_create_connection(
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     ...<7 lines>...
     )
     ^
   File "/usr/local/lib/python3.13/site-packages/aiohttp/connector.py", line 1291, in _wrap_create_connection
     raise client_error(req.connection_key, exc) from exc
 aiohttp.client_exceptions.ClientConnectorError: Cannot connect to host ntfy.host.xyz:443 ssl:default [Network unreachable]
 
 The above exception was the direct cause of the following exception:
 
 Traceback (most recent call last):
   File "/usr/src/homeassistant/homeassistant/components/ntfy/__init__.py", line 34, in async_setup_entry
     await ntfy.account()
   File "/usr/local/lib/python3.13/site-packages/aiontfy/ntfy.py", line 257, in account
     return Account.from_json(await self._request("GET", self.url / "v1/account"))
                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   File "/usr/local/lib/python3.13/site-packages/aiontfy/ntfy.py", line 96, in _request
     raise NtfyConnectionError from e
 aiontfy.exceptions.NtfyConnectionError

I still can't figure out what might be causing this. Everything to my ntfy instance works, except HA. I can also ping the host, get correct DNS resolution to the host, send notifications via cURL to the host, all inside the HA container. Only aiohttp seems to have issues with it.

I even created a python script with

import aiohttp
import asyncio

async def main():

    async with aiohttp.ClientSession() as session:
        async with session.get('http://ntfy.host.xyz') as response:

            print("Status:", response.status)
            print("Content-type:", response.headers['content-type'])

            html = await response.text()
            print("Body:", html[:15], "...")

asyncio.run(main())

even that works without any problems inside the HA container....