pyrogram/docs/source/faq/socket-send-raised-exception-oserror-timeouterror.rst

socket.send() raised exception, OSError(), TimeoutError()
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If you get this error chances are you are blocking the event loop for too long.
In general, it means you are executing thread-blocking code that prevents the event loop from
running properly. For example:

- You are using ``time.sleep()`` instead of ``asyncio.sleep()``.
- You are running processing loops that take too much time to complete.
- You are reading/writing files to disk that take too much time to complete.