BLZBNTAGT00000BB8 is a generic error that means the Blizzard Desktop Application is unable to complete it’s assigned task and it doesn’t know why.
The typical causes are going to be network/connection related, corrupt desktop application/client specific or due to some sort of software/permission conflict.
The following steps should help:
Try doing an extended power cycle on your system. Turn off all devices including the modem. Wait 30 minutes, turn on the modem, wait 5 minutes, turn on any network devices, wait 2 minutes, turn on your computer and try the game.
You can try switching your DNS settings to use a free public DNS servers instead of your ISPs Servers:
We do not have individual steps for specific modems or routers so if you need assistance accessing or updating the devices, contact the device maker/provider.
If you have a separate Router and Modem, Please temporarily bypass the router and plug directly into your modem. We only need to do this to test the simplest possible setup and see if the issue is affected in any way so you do not need to keep this setup once we are done troubleshooting. You will need to reboot the entire network and PC to allow the modem to properly connect you to the internet. Once you are done testing just reconnect the router and reboot everything again.
In some cases there is a corrupt or misconfigured setting within the router or modem. We cannot say what that might be offhand but the easiest way to resolve these conflicts would be to factory reset the router and/or modem.
You may need to look up your specific model for the steps on how to do this and in some rare cases you may need to have this done by the ISP. Feel free to reach out to them for assistance if necessary.
Let’s manually clear the Battlenet Desktop Application and all supporting data from the system. This will not remove existing game clients.
- Open file explorer/file manager (Right Click Windows Start)
- Navigate to the folder where the desktop application would normally be installed. Delete that folder if it exists (usually program files x86)
- Type the following into the address bar (not the search bar): %APPDATA% and press enter.
- Delete the Bnet and blizzard folders inside the appdata folder if they exist.
- Repeat steps 3 and 4 with %PROGRAMDATA% %LOCALAPPDATA% and %TEMP%
- Empty the recycle bin.
- Now reinstall the app to the C: Drive.
Try running your system in selective startup mode: https://battle.net/support/article/200483
Create a new administrator account: Creating a New Administrator Account - Blizzard Support
Once the account is created, shut down the computer, wait 60 seconds, restart, log into the new profile and try the app/client.