diff --git a/dom/media/MediaRecorder.cpp b/dom/media/MediaRecorder.cpp
index 18172f23e52b..3be9f83ee936 100644
--- a/dom/media/MediaRecorder.cpp
+++ b/dom/media/MediaRecorder.cpp
@@ -109,6 +109,8 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(MediaRecorder,
                                                   DOMEventTargetHelper)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mDOMStream)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mAudioNode)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mSecurityDomException)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mUnknownDomException)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mDocument)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
@@ -116,6 +118,8 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(MediaRecorder,
                                                 DOMEventTargetHelper)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mDOMStream)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mAudioNode)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mSecurityDomException)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mUnknownDomException)
   tmp->UnRegisterActivityObserver();
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mDocument)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
@@ -1055,6 +1059,9 @@ void
 MediaRecorder::Start(const Optional<int32_t>& aTimeSlice, ErrorResult& aResult)
 {
   LOG(LogLevel::Debug, ("MediaRecorder.Start %p", this));
+
+  InitializeDomExceptions();
+
   if (mState != RecordingState::Inactive) {
     aResult.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
     return;
@@ -1397,12 +1404,27 @@ MediaRecorder::NotifyError(nsresult aRv)
   MediaRecorderErrorEventInit init;
   init.mBubbles = false;
   init.mCancelable = false;
+  // These DOMExceptions have been created earlier so they can contain stack
+  // traces. We attach the appropriate one here to be fired. We should have
+  // exceptions here, but defensively check.
   switch (aRv) {
     case NS_ERROR_DOM_SECURITY_ERR:
-      init.mError = DOMException::Create(aRv);
+      if (!mSecurityDomException) {
+        LOG(LogLevel::Debug, ("MediaRecorder.NotifyError: "
+          "mSecurityDomException was not initialized"));
+        mSecurityDomException = DOMException::Create(NS_ERROR_DOM_SECURITY_ERR);
+      }
+      init.mError = mSecurityDomException.forget();
       break;
     default:
-      init.mError = DOMException::Create(NS_ERROR_DOM_UNKNOWN_ERR);
+      if (!mUnknownDomException) {
+        LOG(LogLevel::Debug, ("MediaRecorder.NotifyError: "
+          "mUnknownDomException was not initialized"));
+        mUnknownDomException = DOMException::Create(NS_ERROR_DOM_UNKNOWN_ERR);
+      }
+      LOG(LogLevel::Debug, ("MediaRecorder.NotifyError: "
+        "mUnknownDomException being fired for aRv: %X", uint32_t(aRv)));
+      init.mError = mUnknownDomException.forget();
   }
 
   RefPtr<MediaRecorderErrorEvent> event = MediaRecorderErrorEvent::Constructor(
@@ -1450,6 +1472,13 @@ MediaRecorder::GetSourceMediaStream()
   return mPipeStream ? mPipeStream.get() : mAudioNode->GetStream();
 }
 
+void
+MediaRecorder::InitializeDomExceptions()
+{
+  mSecurityDomException = DOMException::Create(NS_ERROR_DOM_SECURITY_ERR);
+  mUnknownDomException = DOMException::Create(NS_ERROR_DOM_UNKNOWN_ERR);
+}
+
 size_t
 MediaRecorder::SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
 {
diff --git a/dom/media/MediaRecorder.h b/dom/media/MediaRecorder.h
index 936faaea8deb..5bab46880bf7 100644
--- a/dom/media/MediaRecorder.h
+++ b/dom/media/MediaRecorder.h
@@ -28,6 +28,7 @@ class GlobalObject;
 namespace dom {
 
 class AudioNode;
+class DOMException;
 
 /**
  * Implementation of https://dvcs.w3.org/hg/dap/raw-file/default/media-stream-capture/MediaRecorder.html
@@ -133,6 +134,12 @@ protected:
   void RemoveSession(Session* aSession);
   // Functions for Session to query input source info.
   MediaStream* GetSourceMediaStream();
+  // Create DOMExceptions capturing the JS stack for async errors. These are
+  // created ahead of time rather than on demand when firing an error as the JS
+  // stack of the operation that started the async behavior will not be
+  // available at the time the error event is fired. Note, depending on when
+  // this is called there may not be a JS stack to capture.
+  void InitializeDomExceptions();
   // DOM wrapper for source media stream. Will be null when input is audio node.
   RefPtr<DOMMediaStream> mDOMStream;
   // Source audio node. Will be null when input is a media stream.
@@ -159,6 +166,12 @@ protected:
   uint32_t mVideoBitsPerSecond;
   uint32_t mBitsPerSecond;
 
+  // DOMExceptions that are created early and possibly thrown in NotifyError.
+  // Creating them early allows us to capture the JS stack for which cannot be
+  // done at the time the error event is fired.
+  RefPtr<DOMException> mSecurityDomException;
+  RefPtr<DOMException> mUnknownDomException;
+
 private:
   // Register MediaRecorder into Document to listen the activity changes.
   void RegisterActivityObserver();