Hi,
If you did move the WSUS database file to the non-system driver, just ignore this warning.
If the system drive runs out of disk space, this can lead to corruption of the operating system and denial of service. That's why it is not recommended to put the database and content on the system driver.
Therefore, if you are sure that the database has been moved, it's safe to ignore the warning.
Best Regards.
Steven Lee Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.