The TileDataLayer folder (full path below) Code: C:\Windows\System32\config\systemprofile\AppData\Local\TileDataLayer\ was entirely missing, I created that and the Database subfolder then restarted and then found EDB files were being generated there and the error has gone.
If you use the UUP tool to create your ISO, yes you can upgrade straight from 1803 to 1903 with no problem.
Someone has these images pl_windows_10_consumer_editions_version_1903_x64_dvd_e974ed38.iso pl_windows_10_consumer_editions_version_1903_x86_dvd_2d4baf81.iso Thanks in advance.
Added to OP: 18362.30 SVF Patches by @GezoeSloog https://forums.mydigitallife.net/threads/windows-10-svf-repository.63324/page-160#post-1517461 Now you all can go nuts...
For some users, something is screwed up with this release and installing CU .53 MS has no official solutions at this moment
Does anyone have this German version? Code: de_windows_10_consumer_editions_version_1903_x64_dvd_02343d69.iso
Download "en_windows_10_consumer_editions_version_1903_x64_dvd_b980e68c.iso" and then use SVF to generate EN>>DE ISO.
Added to the OP: 18362.30 Server SVF Patches by @GezoeSloog https://forums.mydigitallife.net/threads/windows-10-svf-repository.63324/page-160#post-1517501
LOL, when I tried to install 1903 and it thought the "Print to PDF" and "XPS Document Writer" drivers were incompatible. Even though they are built-in Windows drivers. Removed them and still ran into the issue. Just deleted the compatibility logs from $WINDOWS.~BT and then refreshed that error page from the Windows setup installer. Finally allowed me to install.