Windows Defender Offline scan won't work

(1) Two repair/upgrade-install's is enough for me to say that isn't a cure. A repair/upgrade install seeks to keep settings. So, normally I'd say a setting is implicated. But you also did a reset which doesn't keep settings (I don't think). So it's still a mystery why a Defender offline scan fails. Are you willing to try a clean install? You've got a master willing to help with that in this thread -- Greg!

(2) I doubt it is a virus or malware issue because you've scanned with many scanners. I doubt any more are necessary. But have you got Secure Boot enabled in BIOS? That one checks for rootkit viruses at the earliest possible moment -- before even the recovery environment can be reached.

(3) I'm unsure whether an offline Defender scan checks for anything more than an Online quick scan checks.  The only virus definitions mine used were found on C: drive, & there's this line in my MsssWrapper.log**:**"Signatures are already fairly recent. Skipping sig update.". But, if it finds a virus, I guess it would be easier to remove. Also, maybe, since Windows & the virus aren't running, the virus can't hide as well.

(4) I'd still like to know whether you can "Reg Query HKLM\SYSTEM" in the recovery environment (Shift+Restart). It would say whether it is Defender at fault or something about your pre-boot environment itself. But that presumes the Defender pre-boot & the Shift+Restart pre-boot are the same.

Thanks for all your help!

Okay I did what you said and it ran just fine. At this point I decided to do another repair upgrade, this time with no updates and only keeping personal files but no apps or settings. I tried the scan again and defender still does the same thing. Also the logs are exactly the same. I'm kind of at a loss as to what to do now. Right now my priority is just making sure this was not a virus or malware causing this issue. Are there any other scans that I haven't already run that you can think of that I can use to be sure my computer is safe? I just need to be able to use that laptop again safely.

Okay, just thought I would let you know. I did another repair upgrade, this time with no updates and only keeping personal files but no apps or settings. I tried the scan again and defender still does the same thing. Also the logs are exactly the same. I'm kind of at a loss as to what to do now. Right now my priority is just making sure this was not a virus or malware causing this issue. Are there any other scans that I haven't already run that you can think of that I can use to be sure my computer is safe? I just need to be able to use that laptop again safely.

You are welcome.

(1) If not a virtual machine, I really can't think why the Registry would be in use in the recovery environment. So, I guess 0x80070020 has to mean something other than what I suspected. But what?

(2) Well, I want to know whether you can access HKLM\system in the recovery environment. That's what defender seems to want to do. Which five sub-keys are you missing? I suppose Defender is going after a sub-key to that, but msssWrapper.log doesn't precisely say which one. It needs information to do the following  (I suspect)...

SetRecoveryEnvironmentKey returned 0x00000000

INFO 2021/03/09 02:55:58:364 TID:1412 PID:1380

Mapping target OS C drive to WinPE C drive

INFO 2021/03/09 02:55:58:364 TID:1412 PID:1380

Mapping target OS D drive to WinPE E drive

INFO 2021/03/09 02:55:58:395 TID:1412 PID:1380

BuildTargetOSDriveMapping returned 0x00000000

Your crash came just before that. It wants to know which drive was C: in Windows, I think. Then the other would be the Recovery partition (which normally doesn't have a letter when booted to Windows).

Thanks for the reply! Yes, I'm not running a virtual machine. 

Also thanks for checking out dotomi.com. I really appreciate that!

Im still checking on the version of the recovery environment and will get back to you on that. But I ran the command to see what HKLM/system entries I have and five of the ones you listed are missing from my computer. Is that odd?