Repair install/in-place upgrade not proceeding normally

I am confused...
After problems with the 2021-06 cumulative update for x64 machines, I had to uninstall the latest quality update.
Now having different problems (no sound devices detected), I wanted to try an in-place/repair install.
Using the Media Creation Tool, I downloaded an ISO and mounted it.
Launching setup didn't give me the option to select which files to keep. I thought, maybe that'll come later, so I went ahead with the installation (choose drive/volume, preparing, restarting...) but it became clear that it was really just a regular fresh installation.
So I rebooted and restored the disk image I'd taken before.
Wondering why it didn't work, I checked my windows version:
It shows as 20H2 (OS Build 19042.985)
Realizing that the MCT now serves 21H1, I used Rufus to download an ISO of 20H2.
Upon selecting the version, I noticed that this build of 19042.985 should usually be 21H1. There is no 20H2 19042.985 O.o

So I tried the 20H2 19042.631 version, but like before, the version didn't seem to want to install as an in-place update.
What do I do? O.o
Is there an .ini or .xml file in the ISO I need to change?
Can I force an in-place update any other way?

Try3 said:

While it is not a topic I have particularly followed, I do recall that if the Version of the ISO used for the Repair install is earlier than the currently-installed Version it will not offer to keep anything.- So it seems to me that you had previously updated to Version 21H1 but then Repair installed with Version 20H2.- I do not know why the MCT would have downloaded a 20H2 ISO since the MCT is now at Version 21H1. Download Windows 10 ISO File - TenForumsTutorials- It will have done a Repair install but will not have preserved anything such as installed apps, your settings and possibly your own files on the OS drive.Denis

Hi Denis, thank you for your quick reply!
Clarifications:
I have not managed to perform any repair install. I aborted the attempted installation which would not let me choose to keep files and restored the image I'd taken before attempting the repair install.
MCT didn't serve 20H2 but 21H1. Only upon discovering that my winver showed 20H2 did I manually download a 20H2 ISO.

- - - Updated - - -

I tried using MCT to start a repair install directly and got this funny message:

��

BTW, so far, all the versions I've tried start me off in a full-screen borderless window, which looks already different from the screenshots and videos I've seen.
Is it safe to assume that something's already gone wrong if this happens, or do I need to go ahead with the installation to see if it could still act like an in-place update/repair install?
(Next would be a warning about moving the old installation to Windows.old, etc)

Try3 said:

I understand that the June update [KB5003637 CU - TenForums] caused the sound problem. Perhaps some of the other contributors to that thread can help you with that.

Already watching :)

Try3 said:

I don't understand which Version you were on before the problem started.

Sadly, neither do I. I didn't think to look at what version my OS thought it was on before going ahead with the latest updates.
I installed the May feature update and everything was fine. I then installed the June update, which broke my system, so I chose to uninstall the last quality update from recovery options. I would have thought that that left me at 21H1 19042.985, but now my winver says 20H2 19042.985 (same build, but old 20H2 name)

Try3 said:

Personally, I'd be tempted to use MCT to get a 21H1 ISO and use that to run a Repair install. This might well be quicker than trying to investigate a problem that 21H1 might solve for you.

That was the first thing I did

Try3 said:

You've added that diagram as I've been typing. What exactly were you doing at the time? [Repair installs use ISOs / Repair USBs rather than the MCT itself].

The error message screenshot?
as per step 6, I chose the "Upgrade this PC now" option.

- - - Updated - - -

Further complicating the issue may be that I'm not sure if this OS install was originally German. The interface language is EN (US) now, but I'm not sure if I started out with German.
My input language (keyboard layout) still is German (I like English, but I'm just too used to my German keyboards), and regional formats are set to German (Germany) as well.

Something may not be reporting things in the most helpful way. A lot of apps get the idea that my default language is German
From what I hear, language discrepancies may also contribute to an in-place update not being possible.
However, I've also tried German ISOs, all with the same behavior (all act like new installs)
❌ Win10_20H2_v2_English_x64.iso
❌ Win10_20H2_v2_German_x64.iso
❌ Win10_21H1_English_x64.iso
❌ Win10_21H1_German_x64.iso

Try3 said:

I have not used the option you chose and I do not understand why it is not doing as you want.
- I use the procedure in Download Windows 10 ISO File - TenForumsTutorials so that I have the latest ISO which I save on my computer for ages. I use the ISO for all my Repair installs but I can make an InstallUSB from it when I want to.
- Once I have the ISO, I return to Repair Install Windows 10 with an In-place Upgrade - TenForumsTutorials

I have had one language complication but it has not impaired my Repair installs.
- My computer was originally "UK English".
- I accidentally once downloaded the US "English" ISO for a Version upgrade.
- The confusion of languages is still evident several Versions later when checking my installation's properties but, as I said, it has not inhibited my Repair installs.
- The problem is not so annoying that I want to do a Clean install.

I retrieve the language properties of my installed Windows using this command in an elevated cmd prompt / PS window

Code:

dism /online /get-intl

Denis

Yes, I only tried step 6 (using MCT directly with "upgrade this PC now") after the preferred methods of deferring to an ISO image failed.
Yeesh, I don't think anybody would like a clean install over this. But it is weird that you couldn't resolve that issue.
What happens when you add/remove display languages?

FWIW, here is the output of dism /online /get-intl for me:
Deployment Image Servicing and Management tool
Version: 10.0.19041.844

Image Version: 10.0.19042.985

Reporting online international settings.

Default system UI language : en-US
System locale : en-US
Default time zone : W. Europe Standard Time
Active keyboard(s) : 0409:00000407, 0809:00000407
Keyboard layered driver : PC/AT Enhanced Keyboard (101/102-Key)

Installed language(s): en-GB
Type : Partially localized language, MUI type.
Fallback Languages en-US
Installed language(s): en-US
Type : Fully localized language.

- - - Updated - - -

Try3 said:

I check the language properties [and several other properties] of ISO files & InstallUSBs using the procedure in
See Full Details about a Windows 10 ISO file - TenForumsTutorials

Wait a minute, the ISOs for 21H1 list version 10.0.19041, but my system says it's at 10.0.19042!
That would explain why the in-place update doesn't work, right?
Thank you for that tip!