Then there is an update block in place stopping the upgrade. You'll just have to wait until they fix the issue. Probably the only way to bypass this is to do a fresh install with the latest version, but I can't guarantee it since I haven't came across any update blocks. I've been trying to find an article listing the update blocks for 1909 but can't find it. I'll post back if I find it.
I had an error similar to that a few months back. Oddly enough, my nvidia drivers were out of date and once I updated those the update ran without an issue. I can't seem to find anyone else that had the same solution, so it might be random that it worked for me.
I would agree with @johnb35 most likely there is a setting blocking the upgrade, and a clean install would almost certainly work.
Check this link that offers various solutions