Put the summary of the bug you're having here
What I expected to happen was...:
I expected to be able to log on and play as usual.
What actually happened was...:
The game immediately crashes.
Steps to Reproduce:
1. Attempt to log on. The game crashes.
This ticket is invalid as it relates to a modified or 3rd party client, server, or launcher.
Any non-standard client/server/launcher build needs to be taken up with the appropriate team, not Mojang.
Any plugin issues need to be addressed to the plugin / resource pack creator.
This site is for addressing issues related to the base unmodded Minecraft.