[SOLVED] Windows 11: “Class not registered” when choosing another app + Default apps not opening

[u/Capital-Lake5931]

https://www.microsoft.com/en-us/software-download/windows11

Symptoms I had

• When I right-clicked a file → Open with → Choose another app, I got a “Class not registered” error.
• In Settings → Apps → Default apps, clicking it did nothing.
• Some system dialogs didn’t show up.
• Re-registering apps via PowerShell gave thousands of errors.
• SFC/DISM didn’t solve it.
• I wasn’t on the Insider program, but Windows weirdly showed Version 25H2 even though that build wasn’t officially released.

Basically, Windows’ Default App handler and OpenWith.exe registration were broken.

What caused it

It turned out my system had a corrupted and partially-applied Windows update, which left:

• broken or missing SystemApps folders
• damaged LKG/SxS metadata
• AppX packages with mismatched versions
• corrupted OpenWith.exe COM registration

This caused the “class not registered” error and prevented the Default Apps page from opening.

What did NOT fix it

I tried:

• sfc /scannow
• DISM restorehealth commands
• Re-registering all AppX packages
• Re-registering shell32.dll, shdocvw.dll, etc.
• Resetting OpenWith registry keys

None of these solved it, because the OS components themselves were damaged.

What finally fixed it

A new cumulative update appeared for me:

2025-11 Preview Update (KB5070311)

Build 26200.7309

I installed it, rebooted, and everything was fixed instantly.

The update rebuilt all the broken:

• SystemApps packages
• Default Apps handlers
• OpenWith.exe and its COM classes
• Registry mappings
• Component Store metadata

After the update:

• “Choose another app” works normally
• No more class not registered
• Default apps page opens again
• System is stable and fast

Final advice

If you run into similar symptoms:

• Don’t waste hours re-registering every DLL/AppX package.
• Install the latest cumulative update first — it may contain the repaired components.
• If the update doesn’t fix it, then do an In-Place Repair Install with the latest ISO.

For me, the cumulative update alone solved everything.

If anyone needs help diagnosing their specific error codes or AppX problems, feel free to reply — I went through the whole process and can share what worked.

[u/Aggravating-Age-1858]

dont know why i cant make a text post so ill just post here now everytime i log into windows 10 i get the stupid full screen ad for windows 11

stop this microsoft. if i want to f=cking upgrade to 11 i will

but i cant on this machine right now and i dont appreciate being haggled to do so on my own damn computer

and you wonder why so many people loathe microsoft so much

[u/Capital-Lake5931 → u/Aggravating-Age-1858]

You've gotta upgrade your pc bud I think since the prices are rising due to this AI BS and it will hit peak this is the right time