Thonny encounters "internal error" in programs calling exit()

[Phoemuex]

I am running Thonny 3.2.1 on Windows 8.1 (64 bit), using Python 3.7.4 (32 bit) and Tk 8.6.9 (downloaded and installed the bundle from the website).

I have a curious issue regarding programs that call exit(). These work fine usually, but in connection with importing tkinter, they seem to cause issues.

Consider the following two-line program

import tkinter
exit()

Saving this program as "test.py" and running it (via F5) causes Thonny to display the following "internal error":

Traceback (most recent call last):
  File "C:\Users\Felix\AppData\Local\Programs\Thonny\lib\tkinter\__init__.py", line 1705, in __call__
    return self.func(*args)
  File "C:\Users\Felix\AppData\Local\Programs\Thonny\lib\tkinter\__init__.py", line 749, in callit
    func(*args)
  File "C:\Users\Felix\AppData\Local\Programs\Thonny\lib\site-packages\thonny\running.py", line 432, in _poll_vm_messages
    if self._pull_vm_messages() is False:
  File "C:\Users\Felix\AppData\Local\Programs\Thonny\lib\site-packages\thonny\running.py", line 440, in _pull_vm_messages
    msg = self._proxy.fetch_next_message()
  File "C:\Users\Felix\AppData\Local\Programs\Thonny\lib\site-packages\thonny\running.py", line 1141, in fetch_next_message
    msg = super().fetch_next_message()
  File "C:\Users\Felix\AppData\Local\Programs\Thonny\lib\site-packages\thonny\running.py", line 942, in fetch_next_message
    self._store_state_info(msg)
  File "C:\Users\Felix\AppData\Local\Programs\Thonny\lib\site-packages\thonny\running.py", line 988, in _store_state_info
    self._update_gui_updating(msg)
  File "C:\Users\Felix\AppData\Local\Programs\Thonny\lib\site-packages\thonny\running.py", line 1015, in _update_gui_updating
    self._loop_gui_update(True)
  File "C:\Users\Felix\AppData\Local\Programs\Thonny\lib\site-packages\thonny\running.py", line 1021, in _loop_gui_update
    self.send_command(InlineCommand("process_gui_events"))
  File "C:\Users\Felix\AppData\Local\Programs\Thonny\lib\site-packages\thonny\running.py", line 791, in send_command
    self._send_msg(cmd)
  File "C:\Users\Felix\AppData\Local\Programs\Thonny\lib\site-packages\thonny\running.py", line 795, in _send_msg
    self._proc.stdin.flush()
OSError: [Errno 22] Invalid argument

NOTE: The same does not happen if one omits the import tkinter!

NOTE 2: This error is not completely reproducible, sometimes the program finishes without the internal error, but at least after running the program three times in a row, I have until now ALWAYS been able to reproduce the problem, in ~15 tries.

[aivarannamaa]

Thank you for the report!

I was able to reproduce it only once (in about 30 trials), but I think I found the solution. Please open the issue again if it persists in upcoming Thonny 3.2.2

[LordzShadow]

This issue seems to persist in Thonny 4.0.0

running exit() the program does not end and clicking on the shell window and pressing enter, Thonny crashes.

Traceback (most recent call last):
  File "C:\Program Files (x86)\Thonny\lib\tkinter\__init__.py", line 1921, in __call__
    return self.func(*args)
  File "C:\Program Files (x86)\Thonny\lib\site-packages\thonny\tktextext.py", line 243, in dispatch
    return fun(event)
  File "C:\Program Files (x86)\Thonny\lib\site-packages\thonny\shell.py", line 1012, in perform_return
    EnhancedTextWithLogging.perform_return(self, event)
  File "C:\Program Files (x86)\Thonny\lib\site-packages\thonny\tktextext.py", line 468, in perform_return
    self.insert("insert", "\n")
  File "C:\Program Files (x86)\Thonny\lib\site-packages\thonny\shell.py", line 974, in intercept_insert
    self._try_submit_input()
  File "C:\Program Files (x86)\Thonny\lib\site-packages\thonny\shell.py", line 1163, in _try_submit_input
    self._submit_input(submittable_text)
  File "C:\Program Files (x86)\Thonny\lib\site-packages\thonny\shell.py", line 1320, in _submit_input
    get_runner().send_program_input(text_to_be_submitted)
  File "C:\Program Files (x86)\Thonny\lib\site-packages\thonny\running.py", line 309, in send_program_input
    self._proxy.send_program_input(data)
  File "C:\Program Files (x86)\Thonny\lib\site-packages\thonny\running.py", line 1057, in send_program_input
    self._send_msg(InputSubmission(data))
  File "C:\Program Files (x86)\Thonny\lib\site-packages\thonny\running.py", line 1050, in _send_msg
    self._proc.stdin.write(serialize_message(msg) + "\n")
OSError: [Errno 22] Invalid argument

[aivarannamaa]

Thanks for reporting this! I'll try to fix it for Thonny 4.0.1

[aivarannamaa]

Fixed under #2433.

[vandega]

this error goes in 4.0.1. after easy code.

python 3.11.0 stabile
windows 11.
CPU: AMD x64

this error goes every time, even if I write print('hello world!).
error about def function. no matter if i use def name (*val) or def name (val) error same. answer goes correct in simple codes but error still popup.

Traceback (most recent call last):
  File "C:\Users\User\AppData\Local\Programs\Thonny\lib\tkinter\__init__.py", line 1921, in __call__
    return self.func(*args)
  File "C:\Users\User\AppData\Local\Programs\Thonny\lib\tkinter\__init__.py", line 839, in callit
    func(*args)
  File "C:\Users\User\AppData\Local\Programs\Thonny\lib\site-packages\thonny\ui_utils.py", line 2244, in poll
    on_completion(proc, out_lines, err_lines)
  File "C:\Users\User\AppData\Local\Programs\Thonny\lib\site-packages\thonny\plugins\mypy\__init__.py", line 110, in _parse_and_output_warnings
    logging.error("Can't parse MyPy line: " + line.strip())
NameError: name 'logging' is not defined
```

`

[aivarannamaa]

@vandega, this was fixed in #2491 and the fix will be available in the next version. In the meantime you can get rid of this error by going to "Tools => Options => Assistant" and unchecking "Perform MyPy checks".