EFI Backup Error 0x8078011E – Access Denied

By | 16th January 2024

Had an interesting one in my backup report this week, and it seems to have started after the recent round of updates.

I noticed that one of my DCs had failed to backup the AD System State – something it had been doing happily for months.

The error in the event log was as follows:

What this means is that something else is accessing the EFI Partition, preventing Windows Backup from accessing it. But what?
It turns out that the culprit is – Windows Backup itself – sort of

It’s actually Windows Defender that is causing the problem, as it’s trying to scan the process “wbengine.exe” as part of its real time scanning

The Fix

This is relatively simple – just add the following processes as exclusions in Defender*

  • wbengine.exe
  • wbadmin.exe
  • vsssvc.exe

The same should be true if you are using another AV solution and encounter this error

Once I had added them in, the backup was successful the next time it ran.


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