VanillaFix gives multiple log of errors with BetterPortals.
Here's one: https://paste.dimdev.org/ezogalicay.mccrash
Not sure what's causing, but the game is not crashing, but a lot of this logs pop-up at once sometimes.

1. Update Better Portals
2. Remove mods until you find the one responsible or only BP+Forgelin is left
3. Post updated crash report

I have too many mods too, but I'm experiencing the same issue with the current version.
https://pastebin.com/Ryn8d18w

If it helps to narrow it down, this crash only occured for me AFTER I left a dedicated server. (The server didn't crash and seems to be fine) Immediately upon ending up on the main menu this crash absolutely spammed from VanillaFix (i'm talking like 16MB of logfiles over 20 seconds or so)

Notably, it was a fresh world and as such should contain zero nether portals.

I have too many mods too, but I'm experiencing the same issue with the current version.
https://pastebin.com/Ryn8d18w

If it helps to narrow it down, this crash only occured for me AFTER I left a dedicated server. (The server didn't crash and seems to be fine) Immediately upon ending up on the main menu this crash absolutely spammed from VanillaFix (i'm talking like 16MB of logfiles over 20 seconds or so)

Notably, it was a fresh world and as such should contain zero nether portals.

Sadly, I didn't have time to make the tests asked by Johni0702 since I'm abroad. But I noticed that a lot of very similar pop-ups happen even after I removed both betterportals and forgelin, caused by "unknown".
So I guess we can definitely state that this is not a problem of this mod.

Anyway, I'll do some tests trying to disable the mods that I have in common with IdrisQe (foamfix, dynamic surroundings, vanillafix, sound filters, passable leaves, JEI, quark, charm, clumps, extra alchemy, inspirations, mousetweaks, phosphor lighting) and see if it solves my problem.

I have too many mods too, but I'm experiencing the same issue with the current version.
https://pastebin.com/Ryn8d18w
If it helps to narrow it down, this crash only occured for me AFTER I left a dedicated server. (The server didn't crash and seems to be fine) Immediately upon ending up on the main menu this crash absolutely spammed from VanillaFix (i'm talking like 16MB of logfiles over 20 seconds or so)
Notably, it was a fresh world and as such should contain zero nether portals.

Sadly, I didn't have time to make the tests asked by Johni0702 since I'm abroad. But I noticed that a lot of very similar pop-ups happen even after I removed both betterportals and forgelin, caused by "unknown".
So I guess we can definitely state that this is not a problem of this mod.

Anyway, I'll do some tests trying to disable the mods that I have in common with IdrisQe (foamfix, dynamic surroundings, vanillafix, sound filters, passable leaves, JEI, quark, charm, clumps, extra alchemy, inspirations, mousetweaks, phosphor lighting) and see if it solves my problem.

Hey thanks! I would go through the process myself but the loading times would make me just bash my head against the wall. That and I still have no idea how to trigger it. It's since not happened even once in my other tests. So it'd be just a mess of trial and error and trial and error and... I really really don't want to do that.