--- a/media/mtransport/transportlayerice.cpp
+++ b/media/mtransport/transportlayerice.cpp
@@ -94,16 +94,27 @@ TransportLayerIce::TransportLayerIce(con
 
 TransportLayerIce::~TransportLayerIce() {
   // No need to do anything here, since we use smart pointers
 }
 
 void TransportLayerIce::SetParameters(RefPtr<NrIceCtx> ctx,
                                       RefPtr<NrIceMediaStream> stream,
                                       int component) {
+  // Stream could be null in the case of some badly written js that causes
+  // us to be in an ICE restart case, but not have valid streams due to
+  // not calling PeerConnectionMedia::EnsureTransports if
+  // PeerConnectionImpl::SetSignalingState_m thinks the conditions were
+  // not correct.  We also solved a case where an incoming answer was
+  // incorrectly beginning an ICE restart when the offer did not indicate one.
+  if (!stream) {
+    MOZ_ASSERT(false);
+    return;
+  }
+
   // If SetParameters is called and we already have a stream_, this means
   // we're handling an ICE restart.  We need to hold the old stream until
   // we know the new stream is working.
   if (stream_ && !old_stream_ && (stream_ != stream)) {
     // Here we leave the old stream's signals connected until we don't need
     // it anymore.  They will be disconnected if ice restart is successful.
     old_stream_ = stream_;
     MOZ_MTLOG(ML_INFO, LAYER_INFO << "SetParameters save old stream("

--- a/media/webrtc/signaling/src/jsep/JsepSessionImpl.cpp
+++ b/media/webrtc/signaling/src/jsep/JsepSessionImpl.cpp
@@ -722,16 +722,17 @@ JsepSessionImpl::GetRemoteIds(const Sdp&
   return rv;
 }
 
 nsresult
 JsepSessionImpl::CreateOffer(const JsepOfferOptions& options,
                              std::string* offer)
 {
   mLastError.clear();
+  mLocalIceIsRestarting = options.mIceRestart.isSome() && *(options.mIceRestart);
 
   if (mState != kJsepStateStable) {
     JSEP_SET_ERROR("Cannot create offer in state " << GetStateStr(mState));
     return NS_ERROR_UNEXPECTED;
   }
 
   // Undo track assignments from a previous call to CreateOffer
   // (ie; if the track has not been negotiated yet, it doesn't necessarily need
@@ -1989,16 +1990,25 @@ JsepSessionImpl::ValidateRemoteDescripti
 
     if (oldMsection.GetMediaType() != newMsection.GetMediaType()) {
       JSEP_SET_ERROR("Remote description changes the media type of m-line "
                      << i);
       return NS_ERROR_INVALID_ARG;
     }
 
     bool differ = mSdpHelper.IceCredentialsDiffer(newMsection, oldMsection);
+
+    // Detect bad answer ICE restart when offer doesn't request ICE restart
+    if (mIsOfferer && differ && !mLocalIceIsRestarting) {
+      JSEP_SET_ERROR("Remote description indicates ICE restart but offer did not "
+                     "request ICE restart (new remote description changes either "
+                     "the ice-ufrag or ice-pwd)");
+      return NS_ERROR_INVALID_ARG;
+    }
+
     // Detect whether all the creds are the same or all are different
     if (!iceCredsDiffer.isSome()) {
       // for the first msection capture whether creds are different or same
       iceCredsDiffer = mozilla::Some(differ);
     } else if (iceCredsDiffer.isSome() && *iceCredsDiffer != differ) {
       // subsequent msections must match the first sections
       JSEP_SET_ERROR("Partial ICE restart is unsupported at this time "
                      "(new remote description changes either the ice-ufrag "

--- a/media/webrtc/signaling/src/jsep/JsepSessionImpl.h
+++ b/media/webrtc/signaling/src/jsep/JsepSessionImpl.h
@@ -29,16 +29,17 @@ public:
 class JsepSessionImpl : public JsepSession
 {
 public:
   JsepSessionImpl(const std::string& name, UniquePtr<JsepUuidGenerator> uuidgen)
       : JsepSession(name),
         mIsOfferer(false),
         mWasOffererLastTime(false),
         mIceControlling(false),
+        mLocalIceIsRestarting(false),
         mRemoteIsIceLite(false),
         mRemoteIceIsRestarting(false),
         mBundlePolicy(kBundleBalanced),
         mSessionId(0),
         mSessionVersion(0),
         mUuidGen(Move(uuidgen)),
         mSdpHelper(&mLastError)
   {
@@ -317,16 +318,17 @@ private:
   std::vector<RefPtr<JsepTransport> > mOldTransports;
   std::vector<JsepTrackPair> mNegotiatedTrackPairs;
 
   bool mIsOfferer;
   bool mWasOffererLastTime;
   bool mIceControlling;
   std::string mIceUfrag;
   std::string mIcePwd;
+  bool mLocalIceIsRestarting;
   bool mRemoteIsIceLite;
   bool mRemoteIceIsRestarting;
   std::vector<std::string> mIceOptions;
   JsepBundlePolicy mBundlePolicy;
   std::vector<JsepDtlsFingerprint> mDtlsFingerprints;
   uint64_t mSessionId;
   uint64_t mSessionVersion;
   std::vector<SdpExtmapAttributeList::Extmap> mAudioRtpExtensions;