I wrote an application on Google Appengine with Jersey to handle simple file uploading. This works fine when it was on jersey 1.2. In the later versions (current 1.7) @FormD
We experienced a similar problem, Jetty wouldn't let us upload files more than 9194 bytes, (all of a sudden - one day), we realised afterwards that someone had taken our user access from /tmp, which corresponds to java.io.tmpdir on some linux versions, so Jetty couldn't store the uploaded file there, and we got a 400 error.