Installing KB4592438, KB4586853 results in "Missing operating system"

Dear reader,

28 December last, I tried installing KB4592438 (2020-12) on my Dell Latitude E6410 laptop with Windows 10 20H2 build 19042.572 64-bit. The PC has an almost new Samsung 860 EVO 2 TB SSD; I bought it last November. The install seemed to run fine, but after restarting the PC, I got the message "Missing operating system" and had to restore Windows with a recent system backup. I only had that backup made because I encountered this problem once before with another update some time ago: the 20H2 feature update. In that case, I was finally able to install the update successfully by doing an in-place upgrade with the Media Creation Tool. I tried that 28 December as well, but the tool, after getting everything ready, only offered me a clean install; the option to keep apps and files was greyed out. A kind person in the Microsoft Community (answers.microsoft.com) told me that this was a bug in the Media Creation Tool and that it could be fixed with KB4586853. So I downloaded that and installed it; unfortunately, at restarting, it led to the same error: "Missing operating system". Most updates install without a glitch on the laptop, but now and again, something goes wrong. This is now the third update where that happens.

The disk is an MBR disk with three partitions: C:, the boot partition; a recovery partition; a D: partition where I keep my data; and a bit of unallocated space to keep the SSD happy. C: only contains Windows and programs. The recovery partition works; I've booted into it and it seems fine. I would prefer storing all data on a separate disk, but since there's no room for that in the laptop, I use the next best thing, a separate partition, D:, for that purpose. FDISK, SFC and DISM all come up with clean bills of health prior to installing the pesky updates. When starting up the PC with a recovery USB after the damage has been done by one of these updates, the partition structure seems to be intact, but C: is not the active partition anymore and its filesystem is "RAW" instead of NTFS. I've noticed that after restoring the backup of the system image, D: is whole and fine and all the data in it is there and uncorrupted. I have the nagging feeling that something really small and simple is going wrong, and that it's a matter of finding out what and then applying a solution just as small and simple .

While it was working properly, I've copied the MBR and track 0 of the disk with MBRTool and tried to put these back when the PC wouldn't boot. According to the program, this was done successfully, but it didn't help. I also tried the boot repair option of Macriums rescue USB. Macrium doesn't see a Windows installation or an active partition on the disk and can't go on from there. I've marked the C: partiition as active with DiskPart, but that doen't seem to "stick", if you understand my meaning. If I mark it as active, then terminate DiskPart, then restart DiskPart, the partition is again not marked active.

So how do I get these updates, especially KB4592438, to install correctly? For the time being, I have hidden KB4592438 with WUShowHideDiag.Cab, but that's obviously just a stopgap until a solution comes along. All help to find one, preferably not: "Do a clean Windows install", will be greatly appreciated.

Regards, Jaap.

Take some of the unallocated space and create a separate 100 MB primary partition. Use the bcdboot command to put the boot files in it, mark it as active and try things with a system partition that is separate than you boot C: drive partition.

NavyLCDR said:

Take some of the unallocated space and create a separate 100 MB primary partition. Use the bcdboot command to put the boot files in it, mark it as active and try things with a system partition that is separate than you boot C: drive partition.

Hello NavyLCDR,

Thanks for replying. As to your suggestion: what would that tell us if it worked, and what if it didn't?

Regards, Jaap.

Well, you will know it worked if you can install the two updates successfully. If it doesn't wok, then you have the same result you had the previous times.

NavyLCDR said:

Well, you will know it worked if you can install the two updates successfully. If it doesn't wok, then you have the same result you had the previous times.

Okay. I'll try it some time this week and come back to you with the results.

- - - Updated - - -

Jaap Verhage said:

Okay. I'll try it some time this week and come back to you with the results.

Hello NavyLCDR,

I tried out your suggestion. I made a mini-partition on disk 0, formatted it, put bootfiles on it with BCDBOOT and marked it as active. I then restarted the PC. All seemed to work well and I think I booted from the new partition.
Next, I installed one of the updates that messed up my system partition and allowed restarting again. This led to the following screen:

"Recovery
Your PC/Device needs to be repaired
The application or operating system couldn't be loaded because a required file is missing or contains errors.
File: \windows\system32\winload.exe
Error code: 0xc0000225
Press Enter to try again
Press F8 for startup settings"

The last two suggestions don't work; the same screen returns immediately. After starting up with a rescue USB, I looked at the disk. It was no wonder winload.exe couldn't be found, because the system partition had the filesystem "raw" again.

So, unfortunately, your suggestion didn't seem to do the trick. Thanks for thinking along, however.

I'm open to new ideas! NavyLCDR or anyone else?

Regards, Jaap.

Bastet said:

instructions I posted on the Microsoft forum?

Please post a link.

Looks like drive or RAM malfunction.