it can not start any of world or server

Put the summary of the bug you're having here

What I expected to happen was...:
i think it is going to0 start the game

What actually happened was...:
the game broke and the site brought me here

Steps to Reproduce:
1. i start minecraft launcher
2. then i click on play
3 .then i click multiplayer mode
4. i click on server and bug happens