Hello, I figured out what's actually causing the error people are reporting, as above (or maybe one of the causes). It's not a mod conflict, although I don't use Valen's Progression, so I can't speak to that.
Issue: What actually happens is the EFT client freezes before reaching main menu. obviously there's the server error people are copy/pasting here. I am rarely getting debug hashes printed so I won't bother repasting the same thing. But it does occur at the same time as the freeze.
Cause: With no other mods installed, enabling the "progressive gear" setting in FAIT config editor causes this issue - it's disabled by default. There aren't many settings I want to tweak from default, so I haven't found any other settings that may also cause the issue. Turning off this setting or resetting configs to default resolves the issue.
I use a fat mod stack and other mod conflicts do not appear to have any relation to this issue (other than mods that would obviously cause conflicts, and were developed to fill the void left by this mod when it wasn't being updated.)
Thanks for your time and I hope this is helpful! Take care.
