Game Crashing Before I Can Log In

Put the summary of the bug you're having here

What I expected to happen was...:
log in to my survival game and normally play my world like i have in many other snapshots and regular updates

What actually happened was...:
it sent me back to the home screen of minecraft and after one or two tries it crashed my game

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