Python-telegram-bot fails on telegram.error.TimedOut, unable to restart (on restart get "coroutine 'Updater.start_polling' was never awaited")

Question

I try to create a simple Telegram bot for my school (so students could receive schedule updates in Telegram). I use python-telegram-bot for this. Here is the code I took from the official tutorial:

application = telegram.ext.ApplicationBuilder().token(token).build()

incoming_message_handler = telegram.ext.MessageHandler(
    telegram.ext.filters.TEXT & (~telegram.ext.filters.COMMAND),
    process_incoming_message
)

start_handler = telegram.ext.CommandHandler(
    'start',
    process_start_command
)

application.add_handler(start_handler)
application.add_handler(incoming_message_handler)
application.run_polling()

It works fine, but we have not that good internet connection and my bot from time to time crashes with telegram.error.TimedOut.

So I decided to use an infinite loop and a try-except to reconnect:

while True:
    try:
        application = telegram.ext.ApplicationBuilder().token(token).build()

        incoming_message_handler = telegram.ext.MessageHandler(
            telegram.ext.filters.TEXT & (~telegram.ext.filters.COMMAND),
            process_incoming_message
        )

        start_handler = telegram.ext.CommandHandler(
            'start',
            process_start_command
        )

        application.add_handler(start_handler)
        application.add_handler(incoming_message_handler)
        application.run_polling()
        
        break # exit the infinite loop
    except telegram.error.TimedOut:
        print('trying again')

But instead of trying again and again and again I get this error on a second try:

Traceback (most recent call last):
  File "bot.py", line 24, in __init__
    application.run_polling()
  File "~/.local/lib/python3.10/site-packages/telegram/ext/_application.py", line 765, in run_polling
    return self.__run(
  File "~/.local/lib/python3.10/site-packages/telegram/ext/_application.py", line 939, in __run
    loop.add_signal_handler(sig, self._raise_system_exit)
  File "/usr/lib/python3.10/asyncio/unix_events.py", line 99, in add_signal_handler
    self._check_closed()
  File "/usr/lib/python3.10/asyncio/base_events.py", line 515, in _check_closed
    raise RuntimeError('Event loop is closed')
RuntimeError: Event loop is closed
sys:1: RuntimeWarning: coroutine 'Updater.start_polling' was never awaited

Answer 1

The actual error is

RuntimeError: Event loop is closed

So python-telegram-bot library uses asyncio library and closes the event-loop by default and you couldn't use it again after catching TimedOut exception. Just tell the library not to close the event-loop, change this:

application.run_polling()

to this:

application.run_polling(close_loop=False)

Edited: And you can wrap to try-except only that run_polling() calling, no need to wrap the whole code. Good luck!