I finally got the upload proof-of-concept application to work on my Ion! As it turns out, the problem was actually the registration page for the university wireless network…

There is a redirect page the first time a new device is connected to the network, which requests some simple information like a name and email address. This page was apparently being loaded behind the scenes in my application, and giving me some strange errors (file IO errors for the website) in the ddms log. I likely would never have discovered that this was the problem, had I not opened up the actual web browser application, as was suggested by this post on Google’s Android Beginners.

Basically, the suggestion found there is to try to access your file upload page in the normal browser (even though that application disables file uploads!) to confirm that you can actually access the page from the phone. I know it saved me a ton of time, so I definitely recommend using this technique