Comment # 5 on bug 1187209 from Stanislav Brabec

Actually, you should ask how to solve your primary problem.

See https://specifications.freedesktop.org/basedir-spec/latest/#basics
There is a single base directory relative to which user-specific runtime files
and other file objects should be placed. This directory is defined by the
environment variable $XDG_RUNTIME_DIR.

So your application probably needs to run a (desktop or maybe UID specific)
daemon and place runtime files somewhere. "su --login" nor "sudo" will not do
it for you. But if you can create a directory and set the variable, your
application should start to work.