There are a lot of Topics about this, PLS FIX IT, this game has no sense without multiplayer.
If you can't solve it, you could refund our money at least. I hope someone of the official suport answer this with something of value, because I was playing with my friend just 1 hour ago and now it doesn't work in any way.
I'm having the same issue. My friend bought the full game and I got the pass. Every time he invites me, I accept it, then nothing happens. It just sits there on the loading screen.
What platform are you playing on?
If on Xbox can you ensure that you both have Xbox Live and you have your account set to Adult Default. Also, please ensure that you are playing on your home console.
On PS4 can you check your PS+ sub is up to date.
If you are seeing the errors on PC can you try disabling your firewall and antivirus and then trying again.
You may run into an issue if you or your friend is playing on IPv4 and the other is on IPV6, and vice versa so it's worth checking.