The Server encountered an internal error and was unable to to complete your request. Either the server is overloaded or there is an error in the app

I have Python flask web application and we have an admin and normal view. Normal view is still working and admin view it was working up to last week, but this week all of sudden its stopped working. We have not modified any of the code and we have not changed/modified configurations:

Configurations:

1. we are using apache http server and redirecting to the wsgi scripts.
2. Python version: 2.7.5 and 3.6.8
3. Flask version '0.10.1'
4. Linux CentOS 7

Tried below Workaround to bring back the application, but still we are getting the same error as "The Server encountered an internal error and was unable to to complete your request. Either the server is overloaded or there is an error in the application". So, Please help/suggest me on this issue.

1. Restarted Linux server.
2. Restarted Web Server.
3. Re-deployed the application.