Archived from the Transloadit support forum. Originally posted on October 11, 2011; details may be outdated, see our docs for current behavior. Original thread
The page initially loads and the upload works fine. After the uploads have completed and the user posts their data the uploader is then re-initialized. If the user attempts to upload more files, the browser navigates to the API where the 404 error is visible. This happens immediately after the user selects a file.
would it be possible that you put this up on a staging environment maybe with BASIC AUTH or so? It would be much easier for me to see how you integrated the jQuery plugin, than going over this by explaining it by chat.