pc.createOffer(function(description) {
   console.log(description);
   pc.setLocalDescription(description);
   socket.emit('received_offer', JSON.stringify(description));
 }, {}, mediaConstraints);

 pc.createOffer(function(description) {
   console.log(description);
   pc.setLocalDescription(description);
   socket.emit('received_offer', JSON.stringify(description));
 }, null, mediaConstraints);

I had a working implementation of WebRTC, using the Adapter.js pollyfill. It was previously working between Firefox and Chrome but now it appears to have a type error on the error handler. I had it set to use null, which still works in Chrome but Firefox now requires {} for an empty error handler (therefore breaking either Chrome or Firefox depending which I use). And it doesn't seem to work with an actual error handler either! Example Code: // Works in Firefox pc.createOffer(function(description) { console.log(description); pc.setLocalDescription(description); socket.emit('received_offer', JSON.stringify(description)); }, {}, mediaConstraints); // Works in Chrome pc.createOffer(function(description) { console.log(description); pc.setLocalDescription(description); socket.emit('received_offer', JSON.stringify(description)); }, null, mediaConstraints);