Pls Help!! :<

So I've never used this but I've tried many things and it still nothing works...

So I joined a java SWEM modded server and I go to join and it comes up with "Failed to synchronize registry data, closing connection"
My mods versions are the same versions with the server's versions and I tried deleting the mods and downloading them again..I'm not sure what to do, I tried switching launchers to see if that's the case but again nothing seems to be working :< please help me :<