Hey there,
So the error BLZBNTAGT00001389 is a Blizzard BattleNet Agent Error, and it pretty much mean what it says in that the update agent is unable to obtain data or apply data to itself or the affected client. This points to either a local network issue or something on the system interfering with the desktop application itself. The following steps should help.
Try doing a power cycle on your system. Turn off all devices including the modem. Wait 60 seconds, 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.
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: Blizzard Support - Creating a New Administrator Account
Once the account is created, shut down the computer, wait 60 seconds, restart, log into the new profile and try the app/client.
If that doesn’t solve the issue, then I recommend submitting a ticket with an msinfo attached for further investigation. (instructions for collecting that msinfo report will be on the form.)
Click your name at the top right of this page, click support, click contact support.