You also need to use proper URI syntax for local file references. It
is not proper to enter an operating-system-specific path, such as \\servername\subdir\file.ext without converting it to a URI, which in this case
would be file://///servername/subdir/file.ext. In general, a file path is converted to a URI by adding the scheme identifier
file:,
then three forward slashes (representing an empty authority or host
segment), then the path with all backslashes converted to forward
slashes.