Win11 update uninstallation failed 0x800f0825

I figured out the reason causing error 0x800F0825, at least in my case.

If you have Windows Sandbox enabled, that is the reason. You have to disable it in the "Turn Windows Features on and off" menu, reboot, then you'll be able to uninstall KB5063878.

In the CBS.log when the error happens there would be lines like this:

2025-08-23 13:09:12, Error CBS Container base layer depends on LCU version greater than '10.0.26100.4946'.: 800f0825 [Error,Facility=(000f),Code=2085 (0x0825)]

The "Container base layer" it's talking about has to do with the Windows Sandbox. Disabling the feature removes that dependency allowing the uninstall to proceed.

You can turn the feature back on after uninstalling the update.