Unable to log in - BLZ51914001

Try the following steps to resolve the issue:

1. Restart your computer before doing any other troubleshooting. This can resolve many program conflicts and other temporary issues
2. Run the repair tool to repair any damaged game files
3. Optimize your internet connection. Your current setup may have issues impacting gameplay
4. Lag and disconnections are often caused by outdated or broken addons. If you use any addons, do the following:
   1. Update any addons that you use
   2. Try disabling all of your addons. Navigate in-game to Main Menu > Addons > Disable All
   3. If all else fails, fully reset your user interface (UI)

Tried everything here?

If the previous troubleshooting steps didn't resolve the problem, you can ask the Blizzard player community for help on the tech support forums (if available) or other community gaming sites. Local computer or network technicians may also be able to help if you've exhausted all other resources.