I'm late to the party here, but we just encountered this as well, and I
think I might be of some help There are two requirements to achieve what
you're looking for. The first, is that the user who is attempting to
upload the new version should also have Contribute access to the
project. This can be done in the Sharing menu of the project, by
clicking on "View" next to the user's name, and changing it to
"Contribute", if they aren't already. (I believe this will also work at
the document level, b...