Windows 10 Pro for Workstation updates fail

HAL2020

I have over 1tb free (unused) on an acer predator g9-951 15" laptop with 64gb of ram and a 4gb graphics ram card, along with a second m.2 drive with more that 1tb free and a sata 3 2.5inch ssd with more than 2tb free. I've run cleanup, optimization, etc. The second M.2 is drive D with games installations, the 2.5inch ssd holds a backup of the C: drive as drive H: and is a 1to1 backup. The update always fails between 25 and 29 percent whether on C: drive m.2 or 2.5inch H: drive. Checked TPM\secureboot enabled, all else seems functional.

Problem with EFI bootloader maybe?

HAL2020

Found the problem. It WAS the efi bootloader. For some reason, my backup program decided to set move the bootloader to the backup drive, and then point that bootloader to drive H with the guid for drive C while setting the main drive efi to use drive C with the guid for drive H. The GUID for the drive partition is used as a failover if the drive letter cannot work (at least for win 10; it will change in win 11, both will have to match), so the bootup was working, but when the security was checked in the updater, the guid's didn't match the drive being updated, and the undater would fail. I used EasyUEFI in trial mode to fix this problem following their own documentation. It worked like a charm. A few clicks to have the program rebuild the bootmanager docs. Fixboot, Bootrec, and the other command line utilities wouldn't work, kept coming back with "multiple devices….." errors, I'm guessing due to the mismatch between the drive letter and the guid not matching. Once this was fixed on the main drive, I ran the same fix for the backup drive, and reduced the backup to instead backup 1to1 the main windows partitions (only the windows install and the recovery partition).