Client PC downloaded till 99% then it drops the patch

Leon Toh 0 Reputation points
2026-08-04T09:23:40.63+00:00

Hi all,

My company is using wsus server 2019 , and connect via intranet to my clients, we deployed win 11 for the client side, and recently we found out client pc download july patch up until 99% and dropped , and the other thing is it took a whole day to download the patch.

i had change wsus iis side to max kb transfer , added .psf MIME type to IIS , Ping Enable is set to Flase, Queue length is set to 25000 , and start mode is set to always running.

on client pc, registry editor i change disableduascan to 1 , NoAutoUpdate to 0 and WUServer and WUStatusServer are pointed to the wsus. and DODownloadMode = 100.

i tried stopped windows update , BITs , and CrpytSVC , deleted all file inside C:\Windows\SoftwareDistribution , and started back all three services , and stopped all HP services , Hotpatch tracking services. then run a gpupdate /force .

the download percentage on windows update gui did increase on a very slow crawl after that , but once it reaches 99% it drops the patches. even the small patches like security updates or windows edge updates are very slow.

Test-NetConnection returned true and on Get-NetAdapterStatistics | Select-Object Name, ReceivedBytes, i did saw the ReceivedBytes increase overtime.

I really dont know what to do next. Please help.

Windows for business | Windows Server | Devices and deployment | Install Windows updates, features, or roles
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  1. Adam J. Marshall 10,871 Reputation points MVP
    2026-08-07T19:18:01.8433333+00:00

    Run a wsusutil reset on your WSUS server

    https://www.ajtek.ca/wsus/what-does-a-wsusutil-reset-do-and-when-should-i-run-a-wsusutil-reset/

    If it's a corrupt file, that will fix it. Once the reset is finished (wait 24h as there's no progress bar), see if the computers are now able to receive the updates.

    You may also want to check to see if the detectoids issue plagues your WSUS server. If you had a licence to WAM, it would alert you if you had the test detectoids Microsoft issued a notice about.

    https://www.ajtek.ca/blog/microsofts-wsus-service-degradation-how-wam-responded-in-record-time/

    I recommend a Delivery Optimization Download Mode of LAN which numerically is 1.

    If the WSUS Server itself is having trouble downloading the updates, you may need to force BITS foreground priority mode.

    https://www.ajtek.ca/wsus/wsus-bits-foreground-priority-mode-vs-background-priority-mode/

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  2. Harry Phan 27,165 Reputation points Independent Advisor
    2026-08-04T11:05:03.13+00:00

    Hello Leon,

    This looks less like a connectivity issue and more like a WSUS content validation or Delivery Optimization problem. If updates consistently reach 99% and then restart/fail, check the client's WindowsUpdateClient Operational log and Windows Update log for the exact error code.

    As a quick test, set Delivery Optimization DownloadMode to 0 instead of 100 and retry on a clean client. Also verify that the affected July updates show 100% Downloaded in WSUS and that the corresponding content exists correctly in the WSUSContent folder.

    The most important next step is to identify the exact Windows Update error code when the download drops from 99%. That code will tell us whether the issue is WSUS content corruption, Delivery Optimization, or Windows component store related.

    Harry.

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