’ve been trying without success to start WoW-Midnight for about a week and a half. Battle.net app has an Update button, but it stops immediately with BLZBNTAGT00001398 - Internal Error occurred. Reboots of my iMac and my router don’t help. Reinstalling Battle.net makes no difference. Throwing out the Agent folder as suggested breaks Battle.net entirely. Trying Scan & Repair gets the same 1398 error message.
Clicking on World of Warcraft Launcher thinks for a while, downloads something to 5%, then gives the BLZBNTBTS0000005C error, for Missing or Corrupted data.
I’ve tried logging into my almost never used Admin account, same results, so it’s not a permissions problem.
Trying some of my older games, SC2 is acting similarly, and Diablo 3 says it patched, but crashes if I try to launch it. Only HotS starts, so I started playing it again yesterday.
I know this iMac is 9 years old, but with a larger screen, larger hard drive, and more memory than the new ones have. This is very frustrating.
These are Battle.net Agent failures, not game failures.
They happen when the macOS version is too old for the modern Agent.
A 9‑year‑old iMac typically caps at macOS 10.13–10.14, and Blizzard quietly dropped support for those versions.
That’s why:
WoW Midnight fails
SC2 fails
Diablo III fails
Scan & Repair fails
Updates stop instantly
Only Heroes of the Storm launches (older engine)
Everything you wrote about Step 01 is correct.
Step 02 — Correct
Old Blizzard folders contain incompatible Agent data.
Reinstalling Battle.net without deleting them does nothing.
Step 03 — Correct
Older macOS treats /Applications as a protected folder.
Modern Battle.net needs real‑time write access.
If the OS blocks writes → “Missing or Corrupted Data.”
Moving games to ~/Applications or ~/Games fixes this.
Step 04 — Correct
Downloads stopping at 5%, multiple games breaking, only HotS launching —
these match filesystem corruption.
Disk Utility → First Aid is the correct fix.
Step 05 — Correct
Reinstalling Battle.net after deleting all Blizzard folders gives a fresh Agent.
Installing into ~/Applications ensures the Agent can write normally.
Step 06 — Correct
If the Mac cannot upgrade past macOS 10.13–10.14, then:
Ventura is still supported by Blizzard, at least nominally. macOS 12 (Monterey) is the minimum requirement for Midnight.
That’s the good news, at least. The bad news is that you’ve done everything you should have done to try and get it to work, and I don’t have any additional suggestions at the moment. Are you playing it on the internal drive, or from an external?
I don’t have any better suggestions, sorry. I would have imagined that permissions errors were the issue, but you’ve investigated that. I suppose your options now are i) sit tight and periodically attempt to update in the event that the problem is resolved, ii) since you’re on an Intel Mac, is BootCamp an option for you? (or, iii, upgrade to Apple Silicon. I’m playing WoW on an M4 Pro mini, and it runs very well indeed).
BLZBNTAGT00001398 – Internal Error