KB4586853

System and user certificates might be lost when updating a device from Windows 10, version 1809 or later to a later version of Windows 10. Devices will only be impacted if they have already installed any Latest cumulative update (LCU) released September 16, 2020 or later and then proceed to update to a later version of Windows 10 from media or an installation source which does not have an LCU released October 13, 2020 or later integrated. This primarily happens when managed devices are updated using outdated bundles or media through an update management tool such as Windows Server Update Services (WSUS) or Microsoft Endpoint Configuration Manager. This might also happen when using outdated physical media or ISO images that do not have the latest updates integrated.

Note Devices using Windows Update for Business or that connect directly to Windows Update are not impacted. Any device connecting to Windows Update should always receive the latest versions of the feature update, including the latest LCU, without any extra steps.

This issue is resolved in KB4592438.

When using the Microsoft Japanese Input Method Editor (IME) to enter Kanji characters in an app that automatically allows the input of Furigana characters, you might not get the correct Furigana characters. You might need to enter the Furigana characters manually.

Note The affected apps are using the ImmGetCompositionString() function.

This issue is resolved in KB5005101.

A small number of devices that have installed this update have reported that when running chkdsk /f, their file system might get damaged and the device might not boot. 

This issue is resolved and should now be prevented automatically on non-managed devices. Please note that it can take up to 24 hours for the resolution to propagate to non-managed devices. Restarting your device might help the resolution apply to your device faster. For enterprise-managed devices that have installed this update and encountered this issue, it can be resolved by installing and configuring a special Group Policy. To find out more about using Group Policies, see Group Policy Overview.

To mitigate this issue on devices which have already encountered this issue and are unable to start up, use the following steps:

1. The device should automatically start up into the Recovery Console after failing to start up a few times.

2. Select Advanced options.

3. Select Command Prompt from the list of actions.

4. Once Command Prompt opens, type: chkdsk /f

5. Allow chkdsk to complete the scan, this can take a little while. Once it has completed, type: exit

6. The device should now start up as expected. If it restarts into Recovery Console, select Exit and continue to Windows 10.

Note After completing these steps, the device might automatically run chkdsk again on restart. It should start up as expected once it has completed.