I play on a server and it always works fine,but for some reason when i join the server now it crashs everytime

Put the summary of the bug you're having here
when i log in to the server i play on it crashes immediately

What I expected to happen was...:

to let me login and start playing

Describe what you thought should happen here

work normally

What actually happened was...:

crashed minecraft

Describe what happened here

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...