The file could not be uploaded because the destination PATHNAME is invalid

The solution by @Loyarc in #6 did it for me. It would be nice for the module to suggest some options such as temporary:// or public://.

I have used public://sites/default/files/testing with success so I agree that the description for the

Upload location

field could include a couple examples so people don't trip up on this.

Anyone want to create a tiny patch?

I might add a little something for the next release so assigning to me.