Symptoms: after successful upload, the build is made unavailable in Itunes Connect, and an email is sent with the message in title.
Similar errors: ITMS-90542, but this is different in that no ITMS error is specified. Also, the key mentioned has the correct value, so that there is nothing to fix.
Result: an app that uploaded fine before Sep 22 can no longer be updated.
What have you tried: Up-/downgrading XCode and Application Loader, modified the mentioned key, uploaded many versions of a simple test application to pinpoint the cause.