Facepalm: Not for the first time, Microsoft has released a Windows 10 update that fixes one problem while introducing another. This time, a patch for the notorious SSD issue has broken Windows Subsystem for Linux 2 (WSL2).

Windows Latest reports that the September 2020 cumulative update (KB4571756) has had an unwelcome impact for some. Users on Microsoft's Feedback Hub and Github bug report forum note that after installing the update, they're receiving an "Element not found" error when trying to run WSL.

While the problem seems to mostly affect devices running Windows 10 version 20H2 (19042), there are reports of it appearing on some machines with version 2004 (May 2020 Update) installed.

"After the KB4571756, I also got this error. I deleted the docker folders in AppData, then uninstalled and reinstalled docker but it didn't fix. It finally worked when I uninstalled the latest windows quality updates. (docker is associated with WSL in this case," wrote one user.

The SSD bug this update fixed was one of the many issues introduced by the Windows 10 May 2020 update. It affected the Defrag utility app in Windows 10 2004---the tool failed to flag the fact that it had performed a scheduled defragmentation on an SSD. This meant that it could end up repeatedly defragging an SSD, thereby potentially shortening its life span.

Microsoft has yet to acknowledge the new problem, so if you've found WSL2 isn't working after installing KB4571756, the only fix right now is to remove the update.

This is the second time in a week that a Windows update has borked a major feature. The September 2020 optional update is affecting some machines' Sleep Mode, with cases of computers repeatedly waking up for no reason, or the low power state not working at all.