An error occured with no mods

[NeckSnapper933]

So technically for a few days I and my friends have been getting the An error occured whenever we try to join eachothers servers and other peoples servers. We dont have mods %100.
Things we ALL have tried:
-Removing and reinstalling the game
-Removing every single file from the game folder and reinstalling too
-Making sure we have no mods, and yes theres none.
-Resetting our connection settings, making sure we dont have any stuff that would mess with the server.
-Restarting our computers

I would believe that our games are cooked. Other people seem to have this issue too.