Validating a remote SFTP backup destination results in: "Cpanel::FileUtils::Permissions::String::str2oct" was given an invalid permissions string

Symptoms

You may receive the following error when validating a remote SFTP backup destination:

Error: Validation for transport "SFTP"  failed: Could not list files in destination:
Cpanel::Exception::InvalidParameter/(XID g85ks9) 
Cpanel::FileUtils::Permissions::String::str2oct was given an invalid permissions string: drw-rw-rw

Description 

When validating a remote SFTP destination, our backup system will parse the output of a directory listing for a unix-like permission string, such as -rw-rw-rw-​. If the permission-string is not unix-like or is incomplete, you will receive this error. This typically occurs when using a Windows-based destination.

Workaround

Ensure the SFTP destination can list files and directories with complete, unix-like, permissions, such as "-rw-rw-rw-"​ or use a standard unix-like OpenSSH server.