I have written a webrtc client in which re-negotiation(re-offer/answer) is required after call gets established. Scenarios such as 1) upgrade calls from audio to video 2)Downgrade call from video to audio I see mozilla/firefox has issues with re-negotiation of SDP( it fails in setting remote description). Any idea why is this a constraint in Mozilla and has no issues with Chrome. We cannot see this issue in Mozilla-Mozilla calls, but only in calls initiated from mozilla to chrome. This issue was not there in firefox 37 but in latest firefox. steps to reproduce: 1) initiate a call from firefox- mozilla 2) upgrade the call from chrome we can see set remote description fail in firefox.