1.8 crash

Put the summary of the bug you're having here
1.8 - 1.10 multiplayer crash
What I expected to happen was...:
Describe what you thought should happen here
i expected my minecraft to run normal
What actually happened was...:
Describe what happened here
When i open my minecraft it works, but when i press "multiplayer" the game crashes and i don't know why.
Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. what??
3. Im from denmark