Windows 11 and updates KB5021255 and KB5021234, various problems appear

The last Patch Tuesday of the year is not optimal. It spawned several cumulative updates that caused various bugs. They affect Windows 10 and 11.

In the case of Windows 10, we have published a dedicated article because the problem is critical. The PC can crash with the key to a BSOD. For Windows 11 the issues are associated with updates KB5021255 for 22H2 and KB5021234 for 21H2. Microsoft hasn’t officially acknowledged any issues so far. However, the reports are multiplying.

Windows 11, various problems appear

In some cases users report problems when trying to download KB5021255 or KB5021234. The installation process failed with a vague error that does not identify the source of the problem. This mainly happens with Windows 11 22H2. Sometimes error code 0x800f081f appears while in other situations the installation failed halfway and the operating system reverts to the previous version without further details.

It is important to emphasize that this type of concern is not new. One of the possible but not universal solutions is to retrieve these updates via Microsoft Catalog Update and then manually launch their installation.

Here are the two links

We specify “not universal” because users have tried this approach but without success. One explains

KB5021255 fails to install and I am getting error 0x800f081f both through Windows Update and the standalone installer obtained through the Windows Update Catalog. I have a Surface Book 2 with Windows 11 22H2.

In other cases, the errors are more problematic if not critical. On some PCs where the installation was successful, performance issues are observed. A bug seems to hit AMD platforms with a complete “freeze” at random times. This lasts a few minutes, then a return to normal behavior is observed. The affected hardware is equipped with a Ryzen 5 4600GE. We haven’t seen any reports of this bug with Windows 11 21H2.

Finally, these two updates do not seem to appreciate the presence of third-party software modifying the Start menu or other functionalities of the operating system. The Start menu may stop working requiring an uninstall of these KBs. A third-party application named “Explorer Patcher” is advanced. If the Start menu does not work, just launch Run (Win + R) and type ” Control Panel “. Then you have to go to “Programs” to search for “Explorer Patcher” or a similar application. Finally, click on the Uninstall button.

KB5021255 and KB5021234 were released as part of a large monthly maintenance. Their content focuses primarily on security. We have fixed 25 vulnerabilities of which 21 are important, one is reduced and three are critical. These use PowerShell CVE-2022-41076 (flaws allowing remote code execution) and SSTP protocol CVE-2022-44676 and CVE-2022-44670 (flaws allowing remote code execution).

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