Windows Server 2019 Cumulative updates fail

Copper Contributor

Hi all,

We have a Windows Server 2019 production server where the cumulative updates keep failing to install since january this year and I'm at my wits end. Currently it's trying to install 2021-02 Cumulative Update for Windows Server 2019 for x64-based Systems (KB4601345) but it keeps failing.

I've tried downloading the update directly from Microsoft as well and manually install it on the machine but this fails as well. I then tried clearing out C:\Windows\SoftwareDistribution\Download and C:\Windows\SoftwareDistribution\Datastore and re-downloading the updates however this doesn't work either. But it does seem to behave differently after this was done, instead of failing it now goes back to "ready to install". Scratch that, it fails with Error 0x800f0985.

I have attached CBS-logs and Windows Update-log.

7 Replies

I also tried installing Update for Windows (KB4601383) as it said on the download portal that it replaces the previous update, but this one doesn't install either.

Does anyone have any ideas?

best response confirmed by JoniLjungqvist (Copper Contributor)

Might try uninstalling the last successful cumulative update, then install the latest SSU


followed by the latest cumulative update.






@Dave PatrickBrilliant, that solved the issue. Thank you so much!

Glad to hear, you're welcome.

@Dave Patrick
This is an excellent answer, uninstalled a bunch of updates, then the latest accumulative went right in
thank you so much!
Was tired of fighting with KB5009557
Had to log in to thank you

@Dave Patrick , when you say to uninstall the last cumulative update, are you referring to the "Cumulative Update for .NET Framework" or to the "Cumulative Update for Windows Server"?

Hard to say, I'd suggest starting a new thread.