One of the more common errors that you can receive when trying to connect is the 'Bad Login' error. It is simply a Minecraft connection error that has to do with authentication getting temporarily mixed up in the system. In an addition to the updated game launcher, running multiple accounts at the same time is difficult. For every new account logged in, the previous account (while running) will be denied access to servers as the new account will. Other errors still occur occasionally however, here a few possible solutions for them: Possible Solutions When getting the "Bad Login" error message, relaunch your Minecraft program. When getting an "Unexpected error" try and re-login to the server. It's generally caused by a build up of lag or if a server is down; Wait it out. Sometimes the Mojang servers are down and EMC can't do anything to fix that. Check this link out and save it on your browser so you can check back if you're getting any issues. Check the home page. If there's ever a planned server downtime for EMC it will be announced here.