TileEntity

Add crash-reports with sites like https://mclo.gs/ Remove chaosawakens

ImmersivePortals is mentioned - is there a change without it?

Is there a log or similar?

Yes

Does it work without Optifine? If yes, replace it with Embeddium/Oculus https://www.curseforge.com/minecraft/mc-mods/embeddium https://www.curseforge.com/minecraft/mc-mods/oculus

strawgolem is not working - remove this mod

Update your AMD/ATI drivers - get the drivers from their website - do not update via system

Add the crash-report or latest.log (logs-folder) with sites like https://mclo.gs/ and paste the link to it here

Also remove randompatches

It is an issue with SolarFluxReborn - maybe a conflict with AE2 Report it to the creator

Add the new crash-report

Add this mod: https://www.curseforge.com/minecraft/mc-mods/advancements-debug

Contact the support of this site

Common mods are Industrial foregoing, botania, create or immersive engineering - but these are not up-to-date for 1.21.1

Make a test without Rubidium

Remove randompatches

Replace Journeymap with this build: https://www.curseforge.com/minecraft/mc-mods/journeymap/files/5616347

Make a test without modernfix

Worldedit Forge is currently only available for 1.20.4 and older

Add the new log

Add crash-reports with sites like https://mclo.gs/ Make a test without tinyallies

Delete the fml.toml file in your config folder

Start the server via run.bat file Before, open the user_jvm_args file and remove the # at # -Xmx4G

Same issue without the mod Essential?

Optifine is currently not compatible with forge