For some reason I’ve had a lot of Windows 10 PCs fail on their Windows Update with the error 0x8024401C . The “why” probably has to do with some secret handshake that I failed to do with the WSUS server, but the fix (such as it is) was hard fought. The trick I’ve found is to force install the next patch in the Windows 10 update tree. The chart to the “tree” is here: https://technet.microsoft.com/en-us/windows/release-info.aspx.  So for example, if I have a system on build 14393 that was last updated in October 2017 I would pull down KB 4052231 and apply that patch.  Reboot, and fingers crossed, Windows Update will work.  Some caveats:

• I always go with the lowest patch that I can find as it might fail and I will need to install the next patch in the tree.
• Sometimes the patch that I need is not in the update catalog to be downloaded which leaves me having to poach it (painfully) out of the WSUS catalog.

To apply “CAB” patches, start and elevated command prompt and enter the command Dism /Online /Add-package /packagepath:./patchName.cab

Running DISM with no switches will also tell you the Build Number of the Windows 10 system.

(In hindsight, given my access to volume licenses downloads, I could have just downloaded the newer Windows 10 ISOs and updated the systems manually, perhaps, but the above method has the novelty of being able to be run remotely).

[Note (9/25/2020): this process seems to have gotten much better with subsequent Windows 10 updates and it’s usually enough to just go the MS Windows 10 download site and kick off a forced update).