Systemprofile just hosts configuration files including one which links to the Desktop folder. The OS is either not finding the data or is unable to read it. The actual Desktop folder is probably still present in its usual location.

I _think_ that may be a magic symlink/bind mount equivalent that gets remapped to the running user's location.

"C:\WINDOWS\system32\config\systemprofile\" is the profile folder (%USERPROFILE%) for the LocalSystem account; it doesn't normally have a desktop folder.

If Windows is trying to find your desktop folder there when you log on interactively, something's gone horribly wrong (but, frankly, that doesn't surprise me with the 1809 update).