Why is my scenario returning to the main menu

[GeckoSlav 4]

My game just doesn't want to open the scenario I have worked on for so long, all that time gone to waste, it's so frustrating, this happened on AOH2 as well, I didn't give it the opportunity to corrupt, I am so damn angry, I just want an answer why hundreds of hours have gone to waste for nothing

[Hahmynt 0]

I wanted to make my own religion with various bonuses and then i had the same problem. I assume you cannot touch main game files? Correct me if im wrong.

[11:59 Development Team 253]

You can fix this issue by doing basic A/B testing (AOC3 doesn't have good error logs). First, try creating a basic scenario with your current modifications. If this basic scenario does not load, we know that it is an issue outside the scenario itself, and has to do with main game files. Then slowly remove features into a backup folder file by file to override them with the default until you figure out what is breaking your game. Additionally, make sure any custom Civilisations aren't corrupting the game (i.e. because ExtraTags are improperly configured with multiple underscores if you changed ideologies).

If you can create a Default scenario where everything works, what you should do is go to your mod folder, go to the map folder (Earth3 by default), then go into your scenario folder. Here you can see all the data for your scenario (events/, Alliances.json, AlliancesSpecial.json, ..., Wasteland.txt). Slowly replace each file with its defaults until you figure out which of your changes was breaking. You should also check the logs if possible (switching to the MP Beta is the easiest way to gain access to Exception logs).