Try-except in while loop: error with closing program

[Gribouillis]

I don't know why you have this error but the approach of opening the same file again and again at a high frequency while another program now and then modifies the file seems fundamentally wrong to me.

I just want to suggest 3 alternative approaches

1. You could use the watchdog module available in pypi. Simply create an observer that watches the directory containing file.txt and does something every time the file is modified. I think this is the best strategy because you are reusing a robust code that was specially designed for this use case.
   
2. You could also check the modification time of the file before opening it, thus avoiding many file openings.
   
3. You could add a small sleep() operation in the loop to lower the frequency of your system calls.