Nostalrius Begins - Quality wow vanilla realm (1.12)

Hi, people try to invite me to a party but I can't join because they say that I'm already in one but it's not true, so I can't join any party and I don't know what to do...
Thanks

Have you tried relogging or fully exiting the game and logging back in? You can also try deleting your WDB and WTF folders while WoW is closed to see if that helps.