In reply to solya54:
Do you use a mod or datapack? If there aren't too many mods, remove them one by one or every five until the problem is solved and you can better identify the mod causing the problem. If you have datapacks, do the same.
Always remember that some "tags" folders will contain a "logs" folder that is probably causing this error. What may be happening in your case is a mod that is adding a "data" folder with "minecraft" (a data package) and modifying the "logs" tag inside that folder and possibly has some name with a small error inside it (usually it's a ",", but it could be some letter etc.). I honestly don't remember how I solved my error, but it must have been this way, just as I wrote it down.
I don't know if I can help you more than that, I don't really remember what I did, my past self up there knew something I missed along the way
A tip: If the problem started recently, start with the mods or the mod/datapack you added recently
Note: If this is happening without a mod or datapack it's possibly a forge error, reinstall the game.