It's not a good idea to delete the default databases folder on the C drive.
Are you trying to upload to your new folder on the D drive? When in the upload process you do you get the error?
The error appears while the server is "Checking file configuration...".
I tried to put a shortcut to "D:\Databases" in the default C-location but this doesn't work.
A hard link can't refer to another partition and isn't supported for directories.
A junction results in the unwanted effect of having 2 Databases-folders in the admin console (which I do not want to avoid confusion).
You may be right that it is not a good idea, but then FM shouldn't document it as
"When following the recommendation for three logical volume partitions segregating a volume
specifically to host databases, the path to that volume is entered here. Keep in mind that the
default path is still active and any databases placed in the default path will open when the server
starts. It is generally recommended to delete the \Data\Databases directory to avoid confusion."