When attempting to enable User Profile Disks on a RDS Session Collection with the VHD files stored on a remote server, you may get the following error:

Unable to create virtual disk template error -800391163

This error can occur if the activation process is not able to set the required security permissions on the folder.

The handling of UPDs is done by the RDS server itself, and therefore, the computer account needs to have full access permissions on the folder where the VHD files are stored. When enabling UPD, Server Manager will automatically attempt to set up the necessary permissions. When this fails, the above error is displayed.

One such scenario can occur if the shared folde  ...
On August 27th 2020 at 12:49, Roland wrote:
Yes thats right ! but there is another source of explanation.
diskpart automount must be enable in order to alllow UPD to work.
Some software installation disable this sometime (veaam proxy for example).
Maybe it helps .