Windows Defender Errors

Hi all. Some strange behavior from Windows 10 Defender and it seems to point to the April Cumulative Update KB4093112 but I'm not positive. It's fine if the moderators want to move this thread.

Prior to the CU, Defender worked perfectly. A very short time after a successful install, the following started happening...

1. Defender updates automatically or manually and has no problem running a manual scan.
2. Defender no longer runs auto scans -- 0x2 error. The other three processes in Task Scheduler show "operation completed successfully".
3. If I restart the computer and leave it idle, Defender will then immediately run a successful automatic scan and reflect that in the Task Scheduler.
4. The very next day in Task Scheduler, what showed as successful the previous day suddely shows all four Defender processes as "terminating unexpectedly" with error 0x8007042b. A few hours later, still on the previous day's date, the three processes change to "completed successfully" and the auto scan process is back to the 0x2 error.

AV scans, Malwarebytes, sfc /scannow and all DISM commands come up perfectly normal. My neighbor set up a brand new laptop the day before the cumulative update and Defender worked as it should. She got the CU a day later and now has the exact same Defender issues.

Any ideas or suggestions? I'm content to see if this sorts out with the big update we're waiting for. If it doesn't, then I might just resort to manual scans or consider a third-party AV.

Thanks for reading!

@Caledon Ken -- seems to help. Thanks for suggestion.

@Caledon Ken -- only issue left is the 0x2 error for automatic scans. Once that shows up in Task Scheduler, if I restart the computer, the auto scan runs successfully. The other errors where the other three processes kept changing from successful to terminated unexpectedly to successful -- 0x8007042b -- are gone.

Hi Ken -- I'm familiar with the thread showing how to change credentials and I did that last week. What I think I may do is run manual scans until the new feature update comes out and see if that creates a 'clean slate'. I did not schedule any scans, this is the automatic one Defender is supposed to do by itself. I can always go in and schedule my own scan which many posters say does work. The strange thing is how the scan fails and then runs properly after restarting apparently finding the file it couldn't with the 0x2 error.

There are rumors on the internet that the new feature update 'might' come out today so I'm going to give this a rest for now and resume after the install (when ever that'll be). I'll be back to let you know what happens. Many thanks for your willingness to share your knowledge. It is most appreciated.

Dave

Ken -- problem solved! Windows Defender has started to run its own automatic scans -- no errors and no need to restart the computer to kick-start as I mentioned in point 3 at the top of this thread. The only change was yesterday's cumulative update KB4093105. I didn't see anything related to Defender in the list of fixes, but it may have straightened out some things from the previous cumulative update on April 10th. Fingers crossed this keeps up. Thanks again for everything!