When I want to play a multiplayer game with a friend, i try to get in the game or they invite me but the world does not load and it tells me " unable to join world"

Put the summary of the bug you're having here

What I expected to happen was...:
Game should load 

What actually happened...:

it just does not load and says " unable to join world"

Steps to Reproduce:
1. Try to join a multiplayer game with your friend 
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