I was previously using Thonny as my IDE which was good. But I wanted GitHub integration so I decided to switch to PyCharm.
I created a virtual environment for the project inside of the project directory and installed all of the packages including Flask, Flask-WTF, Flask-Login, PyMongo, etc.
When I run the file I get 'No module named 'flask''
I am not sure what I am doing wrong!
Switch to virtualenv by your OS-specific command and then install flask and its modules.
For more info: Flask ImportError: No Module Named Flask