Windows 10: Microsoft Defender Antivirus offline scan won't run. Reinstall Windows?

I'm running Windows 11 Pro 24H2, build 26100.3194. Just a check, I tried to run the Defender offline scan on my computer. After opening Windows Security and selecting Virus & Threat Protection, Scan Options, Microsoft Defender Antivirus offline scan, then selecting Scan I get the popup warning that the system will be shutdown and to save my work. Selecting Scan again in the popup does nothing.I did a computer restart thinking that the offline scan would start after the reboot, but Windows just starts normally. Quick scan and Full scan will run, as well as Custom. Offline scan is the on

:)

 

Microsoft Defender Offline Scan

Restored the Macrium Image and got my Recovery partitions back:






So as expected, I had a bunch of updates to do:





After the updates, I gave Microsoft Defender Offline a try and it worked!









And this just shows that I'm back at the latest version build of 20H2:





This one was my fault and I admit I was the culprit of my own troubles. It was just a coincidence that I used Partition Wizard around the same time the Cumulative Updates were going on from Oct 28th to November 11th and it gave me the suspicion to suspect them being responsible for the Offline scan problem.

I mean who the heck would of ever thought that a Recovery Partition would have anything to do with an Offline Scan in an Online world?

A special thanks to OldNavyGuy for his suggestion that a Windows Recovery Partition being deleted was the problem.

 

Microsoft Defender Offline Scan

The same thing happened to me...because I deleted the Recovery Partition on one of our systems.

That also broke Reset this PC in Settings > Update & Security > Recovery

I tricked myself into thinking that the space was up for grabs -





Uh...no -

(Note: MiniTool Partition Wizard calls Disk Management "Disk 0" - "Disk 1")

 

Window defender offline scan logs

Hello,

Windows Security will only show you the last time your system was scanned by Microsoft Defender Antivirus instead of the offline scan tool.

Microsoft Defender Offline Scan log files are stored as a MPLog-YYYYMMDD-HHMMSS.log file located in the C:\Windows\Microsoft Antimalware\Support folder.

Run Microsoft Defender Offline Scan in Windows 11