KB5015818: Release Preview Update for Windows 11 v 22H2 Build 22621.232

Where else would I find Core Isolation? I looked it up in the search, clicked on it and nothing.

Go to Settings. then Privacy and Security, then Windows Security, then Device Security. The top choice on this window is Core Isolation.

Click on the small blue print underneath, "Core isolation details." It will bring you to a screen with Memory Integrity, and one of those slide switches.

Turn Memory Integrity on. (Otherwise known as virtualization based security.)

FYI, first time I did that, it said I needed a newer Realtek audio driver. Got that updated driver from my OEM's support site, installed it, and then no problem turning on memory integrity.

(I could be wrong about this, but initially, you did not need to switch one Memory Integrity to run Windows 11. I seem to recall a note that in one of the Windows 11 Updates, it became mandatory. Although for me, I had already switched it on in Windows 10, just to be sure it worked, when seeing if my PC met all the security requirements.)

Where else would I find Core Isolation? I looked it up in the search, clicked on it and nothing.

If it's on, try turning it off while the update is downloading/installing.

It is on, in my case.

Make sure that core isolation is tuned on in Windows Security and try again.