External hard drives are not support by Blizzard because of the permission, performance, and update issues that can appear. It’s recommended to install on an internal drive. Copying files from another computer is also an option. If you do, make sure that the hidden folders and files are enabled.
The BLZBNTAGT00000BB8 is a fairly generalized error and can be caused by a variety of issues like permission, corrupted files, or connection. There’s a few steps that can help with this error:
- If the game is already installed or partially installed, delete the indices/data folder then run Scan and Repair after.
- Reinstalling the game, if its an option can also help.
- Try the update on a New Admin account. This resets a ton of windows features including permissions and registries even when there is an existing Admin account.
Hopefully, this helps with some of the basics. Our support article can offer some additional steps as well! If it does continue, we’ll want to check on these issues individually. Please contact our Technical Support department with system files and a connection test to the us.patch.battle.net service!