Failed automatic update - KB4489899 and KB4486553

I agree the update problem appears to be gone & time will tell whether it comes back. Every one of your failed updates is superseded by something that did come in well, as you said. Whatever goodies were in the ones that failed have come in through its successor because these are all cumulatives.

Yes, Windows uses the BCD in EFI in carrying out the reboot involved in these cumulative updates. So, it looks like EFI has been fixed. But I'm working up a bigger post about that.

So, curiously, when I went use Windows Update it decided to serve me a new update (KB4497934), which installed successfully without issue. Now it says I'm up-to-date.

I even went to the Microsoft Update Catalog and downloaded KB4489899 (the first update to have failed on this machine), and it says it's no longer applicable to my system.

I'm assuming KB4497934 supersedes KB4489899? Unfortunately now we can't test definitively whether setting the partition ID is what fixed it. There are several other updates that have succeeded or failed in the meantime (log shown below), but it doesn't seem to want to attempt to apply any of the failed ones automatically.

I guess the only way to be sure at this point is to wait and see if any future updates fail in the same way KB4489899 did. If so, I'll be back to report it. Otherwise we'll just assume that the partition ID was the problem.

So, curiously, when I went use Windows Update it decided to serve me a new update (KB4497934), which installed successfully without issue. Now it says I'm up-to-date.

I even went to the Microsoft Update Catalog and downloaded KB4489899 (the first update to have failed on this machine), and it says it's no longer applicable to my system.

I'm assuming KB4497934 supersedes KB4489899? Unfortunately now we can't test definitively whether setting the partition ID is what fixed it. There are several other updates that have succeeded or failed in the meantime (log shown below), but it doesn't seem to want to attempt to apply any of the failed ones automatically.

I guess the only way to be sure at this point is to wait and see if any future updates fail in the same way KB4489899 did. If so, I'll be back to report it. Otherwise we'll just assume that the partition ID was the problem.

Update: Bios is now v1005, didn't change much, though apparently the system drive is now Disk 4 instead of Disk 3 (it looks like it just swapped the addressing order of the two NVMe drives).

Attempting Startup Repair failed (gave message that it couldn't repair it)

Set ID worked, and the system booted into windows as normal (didn't need a Startup Repair). It seems to have correctly determined that the 100-MB partition is the EFI System Partition now, though it's not recognized as FAT32 anymore. This is what Disk Management looks like:

Going to attempt to apply one of the windows updates again to see if this has fixed anything. If not I may try to apply a Startup Repair again.

I doubt my previous installation used an EFI bios, it was built on a motherboard purchased in 2011. But either way, I'm fairly certain that drive wasn't present during install. Likewise I'm pretty sure I installed to unallocated space on Disk 3 since that's the default method one would usually use. But I honestly can't remember well enough to be 100% sure.

Bios version is 0228 (8/14/2018, initial version). I'll probably flash to 1005 quick and then try the Startup Repair and/or SetID methods just to see if they work. But if neither does the job, I'l just wipe it and start over with unallocated space.