New build + new install (jan26), Win10 Home x64 20H2 build 19042.631; Cumulative U/d KB4598242 fails

Copper Contributor

This seems to be a common issue, but I haven't found a report of it on a new install of 20H2.


I've tried Troubleshooter, sfc, Dism but all still end up with the Cumulative update installing to

30% then Restart

35% Restart

"Couldn't complete updates

Undoing Changes"


and cycling through that 3 times.


Checking Updates, there is the same persistent warning that the Cumulative Update has failed.


How do I fix this please?



9 Replies
does Windows update show you any error codes?


Thank you.

0x8007007e and 0x8000FFFF


Are these screenshots any help?

I reviewed the data you provided, I suggest that you perform a Reset using Cloud download.
the cloud download will download a fresh copy of latest Windows 10 for you and automatically reset your PC with it. it will take care of your Windows update problem as well as the corrupted files problem.

you can do so by going to Windows settings => Update and security => Recovery => under "reset this PC" select "Get Started" and follow the on-screen instructions.

(preferably choose to "Remote Everything" when asked, which will wipe everything from the Windows installation drive, C:\ )



Many thanks! I have been wondering whether to do this - a complete new install.


It will mean reinstalling all the applications etc, but I can live with that - a stitch in time and all that.


One thought first, though: I decided to fit a second 1TB SSD in the new build, so that I can clone a backup image onto it once the original drive is running smoothly, and Windows is updating ok; I haven't even formatted that yet. Does MS allow me to install a fresh Win 10 onto that while the other drive is still active? That way I can check that the updates will work on the new drive before going to all the trouble of saving data files, and reinstalling Cubase, Thunderbird etc on the current boot drive.

when clean installing Windows (from USB or DVD etc), you are not in the actual OS environment, so you can install the Windows on any drive you want, and format any drive and partition you want.
but if you decide to leave your current disk and Windows installation, and install Windows on another SSD, you will most likely end up with a dual boot setup, where every time you reboot, you will be asked to choose an OS.

if you don't get that, then you will boot straight into your newly installed OS and you can add your older installation to the boot record easily, to get the dual boot screen after each reboot.

but in my opinion, if that Windows installation got corrupted, no point in backing it up, just make sure you get your personal files out of C:\ drive.
if you have OneDrive sync on then things on Pictures, Documents and Desktop folders will sync automatically.


Thanks very much for this advice. I tried a reset saving Apps and data - in vain. So then reset using Cloud download, as you suggested, removing everything having backed up all data to the 2nd SDD and a USB stick.


Once Windows was running and configured I installed nothing until I'd used Windows Update several times. All seems to be in order, and updates are complete.

You're welcome ^^
glad to hear it's working fine now,

though why did you have to use Windows update several times?


Having installed the list of updates it displayed, it reported Up To Date, but I checked for updates (this has happened before), and sure enough there were more.... Defender, I think it was. 

Ah yes :)
Defender updates, a cumulative update, .NET framework update sometimes if installed on system, device drivers if any of them is missing