Hello, i am having the same problem and It keeps appearing 510 error to me. Is it related to the mods?
If so, when i take off the mods and then put them into the desktop, should I paste the mods ...
@NaokoReyes The easiest is to try if it works without mods. Have you done that ?
Move the mods folder to the desktop and delete the localthumbcache file. The test on a backup of your save. If the error doesn't occur that way, then yes, it's most probably a mod.
You can then use the 50/50 method to find the culprit