Errors: "Drive Not Found" or "Unknown Error 20047" when Running Tabadmin Backup to a Mapped Network Drive

Issue

When performing a tabadmin backup where the target or temp folder is a mapped network drive, Windows returns the following error:

The system cannot find the drive specified
Or
Unknown Error - Unknown Error (20047) - <Tableau Server Install Path>\bin\<mapped drive letter>

Environment

Tableau Server

Resolution

Drive mapping should be handled by using the net use command. While it is possible to map the drive via the Windows GUI, it is most likely the administrator command line will not have access to the mapped drive if done from the GUI. Instead, net use should be run from the administrator command line, ensuring access to the mapped drive.

net use <drive letter>: \\<UNC path to network folder>
The <drive letter> should be a drive letter that is unused by Windows.

Verify the network drive has been mapped by running
net use

The following is an example that may be useful for automated scripts:
net use <drive letter>: \\<UNC path to network folder>
tabadmin backup <drive letter>:\<backupfilename> <options>
net use /D <drive letter>:

Cause

Mapped drives in Windows can only be seen or used by the same user account that created the drive.
Drives mapped in the Windows GUI by a user may not be available to programs which are run as Administrator such as the Command Line.