Updated Skyrim and now MO2 won't load plugins

[PurpleYellowRosa]

I have a very large load order (3500+), which, through a lot of effort, I managed to make remarkably stable. Until, very recently, I decided to update my game from 1.6.353 to 1.6.640, since several mods are no longer supporting the older version. I made double sure to update every SKSE dll, including Engine Fixes, as well as the loader, and then launched the game. But it crashed as soon as it got to the splash screen.

I used the SKSE log to try and find the culprit, which on first glance appeared to be dTry's Key Utils. I disabled that mod and launched it again. I then had to repeat the process a few more times; Precision and TDM were the only mods to actually give me error messages, saying I had an unstable game and should download Engine Fixes (which I have, to seemingly no effect). Upon disabling them and finally getting to the menu screen, I got several notifications from SRD telling me it had failed to parse yaml files, indicating something was still going wrong at runtime.

I then tried starting a new game - and was immediately put at the carriage scene, despite having Alternate Start enabled.

My conclusion is that, for some reason, MO2 is simply not loading a bunch of mod files, including esps. This never happened on 1.6.353. The only time I have ever seen something similar was when I used the Best of Both Worlds version to try to precache grass.

Is this a known issue? Is there any fix beyond going back to 1.6.353?

EDIT: My Engine Fixes log seems to be throwing up errors for every plugin:

https://ufile.io/jffn057e

Edited August 9, 2023 by PurpleYellowRosa

[Mousetick]

errno 24 means "too many open files"

Try setting MaxStdio in EngineFixes.toml to 4096 (or higher if that's still not high enough, 8192 maximum).

[PurpleYellowRosa]

That solved it, thank you!