Our iPhone app (http://audioboo.fm) uploads users' audio over HTTP. If an upload fails for whatever reason (not uncommon over a cellular network), the server responds with HTTP 422, and the phone retries. The phone will continue retrying until it receives HTTP 2xx.
We've had a few users reporting problems where the phone thinks the upload has succeeded (and so stops trying to re-upload), despite the server responding with 422. On investigation, it seems like all of these users were using cellular data, on O2 in Ireland.
I'm working off a small samplesize here - only half a dozen users have actually come to us reporting the issue - and I don't have detailed information on what the app is actually receiving from the server, so this may be complete speculation. However, I think what is happening is that the 422 response is somehow getting transformed by O2's 3G network to a 200.
So -
- does that sound plausible, or have we got something completely different going on