Windows 10 IoT Enterprise UWF Servicing mode not working with UWF enabled?

Question

Using Windows 10 IoT Enterprise LTSC 21H2. We are seeing behavior differences in UWF Servicing mode in 21H2 when compared to earlier builds (such as 1809). At first we assumed it was something we were doing wrong in our scripts or code. However, I was able to remove all of our configuration code save for the stock command line options recommended by the MS docs and I was still able to reproduce unexpected behavior.

The following steps reproduce the issue with a stock Windows 10 IoT Enterprise LTSC 21H2 install.

• Install Windows 10 IoT Enterprise LTSC 21H2
• Add Windows feature Univeral Write Filter (UWF installed but not enabled at this point!)
• Enable UWF Servicing
  uwfmgr servicing enable
  uwfmgr filter restart (causes automatic reboot)

Expected: On the next boot Windows enters Windows servicing mode and displays Updating Device splash.
Actual: On the next boot Windows enters Windows servicing mode and displays Updating Device splash.

After approximately 5 minutes, the Updating Device splash is replaced with the Windows logon screen, with UWF Servicing as the default user account. We interpret the fact that this user account is visible indicates UWF-Servicing mode is still active in the background. Waited 20-25 mins until Windows rebooted to login screen and UWF Servicing account is no longer visible. So far so good. Then I try to enable UWF...

Enable UWF
uwfmgr filter enable
uwfmgr filter restart (causes automatic reboot)

Expected: On the next boot Windows disables UWF, enters Windows servicing mode and displays Updating Device splash.
Actual: Windows boots to the normal login screen. UWF Servicing is not visible. While in this state, if I log in as a normal admin user, uwfmgr get-config indicates UWF is off and lists Servicing State: ON. The machine remains stuck in this state.

On 1809 the above worked and UWF Servicing mode started after enabling it with UWF enabled.

Am I missing something or doing anything int he wrong order in the basic reproduction steps above?

Answer 1

Hi @Bob Rafuse ,

Welcome to Microsoft Q&A!
First of all, i list the points you should notice the things below:

1. We recommend that you use the uwfmgr.exe servicing enable command to service your UWF–protected device whenever possible. Administrator-level permissions are required to use this command.
2. Here is the official document which is detailed: Apply Windows updates to UWF-protected devices.
3. When UWF servicing mode is triggered, Windows does the following:

• Clears the UWF overlay.
• Reboots the devices.
• Triggers a system maintenance hour.
• Disables the UWF filter.
• Scans for and applies Windows updates.
• Scans for and applies app updates from the Microsoft store.
• After servicing is complete, it re-enables the UWF filter and resumes UWF protection.
  If you check your steps have no problem, this maybe the bug of Windows 10 IoT Enterprise LTSC 21H2. You can post your issue in feedback website: https://feedback.azure.com/d365community/forum/fcb810f7-f824-ec11-b6e6-000d3a4f0da0

Best regards,
Seeya

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