Hi,
As far as I know, there is no related known issues has been offered.
https://learn.microsoft.com/en-us/windows/release-information/status-windows-10-2004
We suggest that you download and run Activation troubleshooter by clicking on this link.
This will let you automatically diagnose Windows activation errors and provide you a remedy.
Since the version 2004 is not so stable, you could roll back to the earlier version and defer the update altogether.
We recommend that you do not attempt to manually update using the Update now button or the Media Creation Tool until this issue has been resolved.
Also, you can use the Feedback Hub app to share your problem and wait for the next update.