I have the same issue .
This system is mainstream parts, off the shelf .Never had an issue with any previous upgrade to and including ver 1909 . But the latest will not install.
The files download, "installing" takes its usual 20 minutes and the system reboots, (but sometimes not), yet once back to the desktop, windows 10 ver 1909 remains the OS. The error is described in Settings as " We could not install the upgrade but you can try again if you like. Error 0xc0000005." I have, many times, using the upgrade method in Settings and the iso file from windows download.
It appears that not many users have this particular problem although the upgrade has created issues once installed. I spent Sunday afternoon with an MS Tier 3 technician to no avail--We did everything he could think of including a few "out there" ideas, like updating the bios, but in the end he took all the logs, will go over them with his team and come back later . I wonder if the next Tier includes Bill Gates ?
The one useful item coming out of this, besides the new bios, is the method of installing of which I was unaware. The upgrade does not install automatically. It only installs if the user hits the " Download and Install" button. The system will continue just as well without it. Which is what I see as the future for this system until the next Feature Update comes along.