If you experience problems with World of Warcraft after patching, first check the Realm Status page to see if your realm is currently online. If your realm is online, try the following:
Reset your user interface to make sure your files and addons are not corrupted.
Update or temporarily uninstall any security programs, which may mistakenly identify the login module as a security threat.
- Configure firewall and proxy settings for World of Warcraft.
- Restart your computer.