Old Windows 10 build and error 0x80004005 while upgrading

I encountered a few computers having obsolete Windows 10 build, like 16.04. This build is not supported for a while, but Windows Update should help here, right?

When running Windows Update from the settings app, I got a notification that version 20H2 was available. Cool, isn’t it? But the upgrade process always ended with error code of 0x80004005. I tried to repair Windows update, as is generally recommended to tame this bug, but with no success. Uninstallation of antivirus app didn’t help either.

Then, I created manually a media with the latest Windows 10 build and tried to upgrade from this media, but again, no luck. This time, I got a simple “cannot upgrade” message after attempting to update the computer.

It turns out that the upgrade process doesn’t like too large distance between original and target builds. So, the only solution for me was to find a medium with 18.04 build, install it (successfully this time) and only then, it was possible to run the upgrade with 20H2 media.

Surprisingly, this doesn’t seem to be documented anywhere, so just in case, this is the solution I succeeded with: 16.04 -> 18.04 -> 20H2, both upgrades done from the installation media, rather than through Windows update. Clumsy, but at least working.