amazon ec2 - Flask- Cannot read or write to file -

I am using AWS EC2 to host a flop application and when the user submits I Attempting to read and write a form using the Open () function, I get an error when the form is submitted:

Internal server error server encountered an internal error and completed your request Was unable to do Either the server is overloaded or there is an error in the application.

I am not sure why this error is happening.

Such a code is:
@App.route ("/ submit", methods = ["POST"])

  Def submit (): file = open ("settingsfile.txt", "w") File.close ()