I'm making an overhaul mod for myself and I'm halfway done doing the 'Country' category for the starting nations. I wanted to save it if a crash happens or something but the problem is that I'm getting a Server Error 500.

EDIT: NOW IT EXPORTED, SOLVED

How did it resolved ?

I just tried it the fourth time and it exported perfectly. lol

If you had a large amount of custom images to, for example if you have uploaded 100 custom leader portraits for your countries, then this could have been the cause. The server will timeout if a process takes more than 5 minutes to complete, and as it has to convert the image format for all images to one the game understands, this can cause the process to take more than the timeout limit; this conversion only happens on exporting the image for the first time though, so shouldn't happen again in the future.

Should you continue to have the issue in the future though, please do let me know and I'll look into it. 

mostly used portraits from the site but uploaded around 200 custom flags so thanks