Loading or Creading Singleplayer worlds

[Daesereg]

The game crushes if i load/create worlds on singleplayer.

I use some mods, optifabric, carpet, extracarpet, phosphor, lithium, some datapacks, but these are used on multiplayer server that i own.

[LOuroboros]

Same here. Trying to use Optifine via Optifabric makes my single player worlds crash. They load up correctly once I remove them though.
I'm personally using the latest preview release of Optifine (OptiFine 1.16.1 HD U G2 pre2) with Fabric Loader v0.8.8 Build 202, Fabric API v0.14.0 Build 371 and Optifabric v1.1.0 Beta 2.

Here's my crash log, in case it helps: https://pastebin.com/nattB41q

One of my worlds is a Superflat Creative one, and at first I thought it got corrupted somehow since I created it back during the snapshot 20w12a, but even though I recreated it on the 1.16.1 it still crashed.

EDIT: Removing Lithium solves the issue. There's this post in its GitHub repository stating that it's incompatible with Optifine.

[sp614x]

Fabric is not supported.
If there is a problem it has to be fixed by OptiFabric.