Domain Joined Windows 10 Slow Boot after updates

Esher College IT Services 106 Reputation points

A few weeks ago after some Windows updates were deployed through WSUS, Windows has become very slow to boot. At first it appears as though it's trying to process a start up script, but nothing is logged in event viewer regarding any group policies and slow processing, the only thing that does appear is this:
"The winlogon notification subscriber <GPClient> took xxx second(s) to handle the notification event (CreateSession)"
It takes over an hour to get from the initial Applying Group Policy Settings screen to the login screen, and when rebooting takes a few minutes at Shutting Down Service: Group Policy Client.

Things I have tried:
Installing Windows 10 fresh in a clean OU, then applied all the policies one at a time to mirror our standard structure. Windows booted fine, until I ran Windows update that installed some security updates, after that I got the slow boot.

Then I tried a fresh install, installed all the updates, and then applied the policies, and the machine was fine, no slow boot.

I am now going through trying to uninstall updates, but Windows won't let me uninstall the security updates and I fear it may be one of those causing the issue.

So it seems that whichever update it is (if it is an update causing the problem) if the update is installed before group policies are applied then there is no issue, but if the update is installed to a machine that already has policies, it causes slow down.

Now I could build a new image and capture in WDS, but then I'd have to go round 1000+ computers and re-image them again!

Has anyone else experienced this issue and maybe a fix?

Windows 10
Windows 10
A Microsoft operating system that runs on personal computers and tablets.
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  1. Esher College IT Services 106 Reputation points

    Nevermind, turned out it was a rogue script running in a group policy, just didn't log in event viewer!
    We ended up enabling UserEnv logging to see what was going on, which led to the GP that was causing the issue

    Enabling UserEnv Logging:

    A log file can be written by the service when implementing the following registry value:

    [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Diagnostics]


    The resulting log file will be


    Note if the logfile is not created, ensure that the folder exists: %WINDIR%\debug\usermode\

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  1. Reza-Ameri 16,861 Reputation points

    In case you confirmed this is an issue after your installed update, then open start and search for feedback and open the Feedback Hub app and report this issue.
    In case you want to investigate this issue, look into logs in the Event Viewer.

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  2. AliceYang-MSFT 2,086 Reputation points


    Thank you for the details you provided. I will discuss with colleagues in WSUS team about this issue when they are back to the office. They may have encountered similar issues before.

    Before that, please check whether these solutions help
    Winlogon Notification Subscriber taking foever!
    In Windows 10, the group policy is in Computer Configuration/Administrative Template/System/Scripts

    How to Fix Windows 10 Slow Boot after Update

    Please note: Information posted in the given link is hosted by a third party. Microsoft does not guarantee the accuracy and effectiveness of information.


    If the Answer is helpful, please click "Accept Answer" and upvote it.
    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

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  3. Esher College IT Services 106 Reputation points

    Thanks for the replies, I will check out those links. After some more investigating it seems that installing any update causes the slow down, not any specific update. I built a new image with all updates installed, captured and deployed it to a couple of machines, ran windows update on one and instant slowdown after reboot, the other rebooted fine several times until I ran windows update, which installed the latest defender definitions, then instant slow down after reboot again :(
    So I don't know if it's the process of just running windows update, the fact that it's on an internal WSUS, or what. Slowly starting to loose my hair!

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  4. Zine Eddine B 1 Reputation point

    If you record a boot trace with Windows Performance Recorder it can help to identify the problem?

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