Failure to install KB5066791 on Win 10 after end of support
brucine Posted messages 24378 Registration date Status Membre Last intervention -
Hello everyone,
I'm encountering a blocking issue with the Windows 10 machines of an association that I'm just starting to help with IT maintenance on a voluntary basis.
I wanted to install the latest security patch offered by Microsoft on several Windows 10 computers, but the installation failed. It apparently did not trigger automatically before the official end of support date (October 2025), and yesterday, when attempting to do it manually, it didn't work either.
Here are the technical details and the actions taken:
Attempted installation of the following patch: October 2025 Patch Tuesday (KB5066791). Issue: Fixing 172 vulnerabilities (including 6 zero-days).
Actions performed and issues encountered:
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Via Windows Update: The installation fails with the explicit message: "Your version of Windows has reached the end of support". This seems absurd as this patch was released and offered before the end of support.
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Via Microsoft Update Catalog (Manual installation): I downloaded the corresponding .msu, but the installation fails immediately with the error: "The update is not applicable to your computer".
My questions:
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Are there any known bugs preventing the specific installation of KB5066791?
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Is this an "administrative" block from Microsoft? In other words, is it possible that the OS refuses to install an update (which is legitimate and released before the deadline) simply because the attempt to install it occurs after the end of support date?
Any leads to work around this block would be welcome to secure these machines, as I am unable to upgrade to Windows 11 immediately.
Thank you in advance for your insights!
Have a great day,
2 réponses
Hello
On a a Windows 10 Home PC that only awaits what the update offers. (for "testimony")
But the last KB presented as 11-2025 bugged, with the same message you've reached the end of support. Just let it go...
Then, a big week later another KB was offered and it went through fine, via update. (the antivirus always updates through its own channel as well.)
No answers and I'm not looking for them, I'm not forcing anything.
Hello
It happens that some updates remain pending, deployment is sometimes random, which could be the case for brucine in "4", in this case if the release date was before the end of support, the update will proceed without issue, even after the blocking date which only affects updates published from November onwards.
And for the ESU, I confirm that you must first install the KB5071959 otherwise you cannot register.
Ps: The Microsoft site is available, there are similar cases
https://learn.microsoft.com/en-us/answers/questions/5632961/windows-10-update-kb5066791
Hello,
Unless the new ESU procedure for Windows 10 has changed the game (there was already a paid one for Windows 7), the end of support means no new updates, but previous updates continue as long as the Microsoft server is active.
This was the case for the many Windows 7 reinstalls I did not so long ago.
KB5066791 is not the latest but the second to last update; since then, there’s KB5071759 supposed to fix a bug where the ESU enrollment is not displayed.
There were on my Windows virtual machine the first one accompanied by a .NET Framework update on October 15 and the second on November 14, so in any case after the end of support date.
Note that even if this update occurs, it is found, as noted in the topic, an average of 150 new theoretical vulnerabilities monthly: in the absence of ESU, this single update is therefore void and of no effect.
Only a more or less obscure bug is reported where the update installs fine but the end of support is displayed despite the ESU being activated, with a fix for this display bug:
https://support.microsoft.com/fr-fr/topic/14-octobre-2025-kb5066791-builds-du-syst%C3%A8me-d-exploitation-19044-6456-et-19045-6456-657e5143-6c5d-4401-8efa-1641ca93c051
Otherwise, it is that quite "classically" something in Windows Update or Windows itself is opposing the updates, see for example the link in <2>.
Moreover, it's incomprehensible, I just have a new security update pending even though I didn't request it and I'm not subscribed to the ESU.
Hello
It's confirmed then, don't worry, more will come as a surprise...