I'm trying to upload my renpy game onto itch.io but I keep getting this error 'cannot find application entry point (main.py) invalid filesystem image'? How can I resolve this? For a bit more context, I was able to upload my game onto newgrounds, just don't know why it doesn't work on itch.io.

Any help would be much appreciated!

Are you sure you uploaded the same exact file? I wasn’t able to get the export of the game working even on my local webserver. I got the same error.