BLZBNTBNA00000005

The Battle.net desktop app failed to communicate with the Battle.net Update Agent, which is required to install, update, launch, and uninstall Blizzard games.

1. Update your drivers to resolve any compatibility issues.
2. Run a security scan to remove any viruses or malware infections.
3. Disable or temporarily uninstall any security programs, which may mistakenly identify the login module as a security threat.
4. Create a new administrator account to resolve permissions issues.
5. Uninstalling and reinstalling the Battle.net App may resolve rare launcher issues.