I close the world with the “Save and Exit” button, after which shutting down internal server appears, literally for two seconds, after which the world closes, and you can enter it again without any problems, i.e. it is saved, but for some reason when exiting it it throws shutting down internal server. At the same time, everything is fine in vanilla - after clicking “Save and Exit”, a blank screen with earth blocks appears and the world closes without any inscriptions.
this happens on version 1.12.2 with forge installed - without it everything is fine.
There are no mods and there never were, only forge.
minecraft license, launcher is also official
what I have already done:
1) deleted options.txt
2) reinstalled minecraft and launcher
3) reinstalled Forge - three latest versions, all with this error
4) I tried it with Optifine - the same thing
what can be done and is it necessary to do anything about it?