In certain environments running Windows 11 version 24H2, you may encounter installation error 0x800f081f when installing cumulative update KB5050009.
Error code 0x800f081f (CBS_E_SOURCE_MISSING) means the component store is corrupted (the source for the package or file cannot be found).
If you encounter this error, first check your Windows Update history.
To open your Windows Update history:
Press Windows Key + R to open Run, type the following command and press Enter:
ms-settings:windowsupdate-historyIs KB5050009 already installed? Check the update history from top to bottom.
For example, in my environment, KB5050009 was installed on 2025/01/15 (blue frame), but since then, it has repeatedly tried to install and failed (red frame).
Checking the OS build also confirms that it has been updated to KB5050009 (OS Build 26100.2894).
4 ways to check the specs (performance, specifications) of your Windows 10/Win11 PC
If KB5050009 keeps installing even though it's already installed, it's most likely a Windows feature.
For example, I am using the Home edition of Hyper-V, and after installing KB5050009, I am no longer able to connect to virtual machines.
In this case, I was able to connect to the virtual machine by running the batch file again, but the current problem occurred immediately afterwards.
Since the feature (Hyper-V) that is not available in the Home edition is enabled, it is not surprising that this problem occurs.
If you are experiencing the above issue with the Home edition, as I did, I recommend leaving it as is until the next update is released.
For example, if you uninstall KB5050009 in this state, the message "メモリ整合性" will automatically be turned "off" and you will not be able to turn it "on", and even if you try to install KB5050009 again, it may fail. (After verification,System restoreI recovered with
I also tested it on Windows 11 Pro, but after enabling Hyper-V, Windows Update screenWhen I checked for updates, the installation of KB5050009, which was already installed, began.
However, in the case of the Pro edition, the installation was successful and it no longer appears.
2025 / 01 / 30:
While I was experiencing the installation error 0x800f081f for KB5050009, I tried to install KB5050094, which was preview released on 2025/01/28, but the same error message appeared and the installation failed.
When I download KB5050094 (msu file) from the Microsoft Update Catalog and run the installation, I get the error 0x800f0838.
According to Microsoft, error 0x800f0838 (0x800f0831) occurs for the following reasons:
- This issue occurs because the update that cannot be installed requires a manifest from a previous update package.
*There is no information on error number 0x800f0838, but we have determined that the cause is almost the same as that of the similar number 0x800f0831.
Microsoft says that this can be resolved by repairing the Windows image and system files and then rebooting, but this did not work in my environment.
From this symptom,Do not force enable features that are not originally available in Windows 11 Home edition.I understand that.
Perhaps Microsoft has quietly implemented a solution to the problem of features that are only available in the Pro edition being enabled in the Home edition.
I'm not sure why, but I guess it's a security issue.
2025 / 01 / 31:
We have found a solution for when you are unable to install the Windows 11 version 24H2 cumulative update KB5050009.
In my environment, all of the above issues have been resolved and Hyper-V is now running without any issues on the Home edition.
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