diff --git a/dom/media/fmp4/wmf/WMFMediaDataDecoder.cpp b/dom/media/fmp4/wmf/WMFMediaDataDecoder.cpp
index 6091e8b85166..32c9785fdca4 100644
--- a/dom/media/fmp4/wmf/WMFMediaDataDecoder.cpp
+++ b/dom/media/fmp4/wmf/WMFMediaDataDecoder.cpp
@@ -8,6 +8,7 @@
 #include "VideoUtils.h"
 #include "WMFUtils.h"
 #include "nsTArray.h"
+#include "mozilla/Telemetry.h"
 
 #include "prlog.h"
 
@@ -44,6 +45,39 @@ WMFMediaDataDecoder::Init()
   return NS_OK;
 }
 
+// A single telemetry sample is reported for each MediaDataDecoder object
+// that has detected error or produced output successfully.
+static void
+SendTelemetry(HRESULT hr)
+{
+  // Collapse the error codes into a range of 0-0xff that can be viewed in
+  // telemetry histograms.  For most MF_E_* errors, unique samples are used,
+  // retaining the least significant 7 or 8 bits.  Other error codes are
+  // bucketed.
+  uint32_t sample;
+  if (SUCCEEDED(hr)) {
+    sample = 0;
+  } else if (hr < 0xc00d36b0) {
+    sample = 1; // low bucket
+  } else if (hr < 0xc00d3700) {
+    sample = hr & 0xffU; // MF_E_*
+  } else if (hr <= 0xc00d3705) {
+    sample = 0x80 + (hr & 0xfU); // more MF_E_*
+  } else if (hr < 0xc00d6d60) {
+    sample = 2; // mid bucket
+  } else if (hr <= 0xc00d6d78) {
+    sample = hr & 0xffU; // MF_E_TRANSFORM_*
+  } else {
+    sample = 3; // high bucket
+  }
+
+  nsCOMPtr<nsIRunnable> runnable = NS_NewRunnableFunction(
+    [sample] {
+      Telemetry::Accumulate(Telemetry::MEDIA_WMF_DECODE_ERROR, sample);
+    });
+  NS_DispatchToMainThread(runnable);
+}
+
 nsresult
 WMFMediaDataDecoder::Shutdown()
 {
@@ -65,6 +99,9 @@ WMFMediaDataDecoder::ProcessShutdown()
   if (mMFTManager) {
     mMFTManager->Shutdown();
     mMFTManager = nullptr;
+    if (!mRecordedError && mHasSuccessfulOutput) {
+      SendTelemetry(S_OK);
+    }
   }
   mDecoder = nullptr;
 }
@@ -100,6 +137,10 @@ WMFMediaDataDecoder::ProcessDecode(MediaRawData* aSample)
   if (FAILED(hr)) {
     NS_WARNING("MFTManager rejected sample");
     mCallback->Error();
+    if (!mRecordedError) {
+      SendTelemetry(hr);
+      mRecordedError = true;
+    }
     return;
   }
 
@@ -115,6 +156,7 @@ WMFMediaDataDecoder::ProcessOutput()
   HRESULT hr = S_OK;
   while (SUCCEEDED(hr = mMFTManager->Output(mLastStreamOffset, output)) &&
          output) {
+    mHasSuccessfulOutput = true;
     mCallback->Output(output);
   }
   if (hr == MF_E_TRANSFORM_NEED_MORE_INPUT) {
@@ -124,6 +166,10 @@ WMFMediaDataDecoder::ProcessOutput()
   } else if (FAILED(hr)) {
     NS_WARNING("WMFMediaDataDecoder failed to output data");
     mCallback->Error();
+    if (!mRecordedError) {
+      SendTelemetry(hr);
+      mRecordedError = true;
+    }
   }
 }
 
diff --git a/dom/media/fmp4/wmf/WMFMediaDataDecoder.h b/dom/media/fmp4/wmf/WMFMediaDataDecoder.h
index ee16ef4ec9d0..f97c46a7ec1b 100644
--- a/dom/media/fmp4/wmf/WMFMediaDataDecoder.h
+++ b/dom/media/fmp4/wmf/WMFMediaDataDecoder.h
@@ -109,6 +109,10 @@ private:
   bool mIsFlushing;
 
   bool mIsShutDown;
+
+  // For telemetry
+  bool mHasSuccessfulOutput = false;
+  bool mRecordedError = false;
 };
 
 } // namespace mozilla
diff --git a/dom/media/fmp4/wmf/WMFVideoMFTManager.cpp b/dom/media/fmp4/wmf/WMFVideoMFTManager.cpp
index 7932f6692407..471989d8c223 100644
--- a/dom/media/fmp4/wmf/WMFVideoMFTManager.cpp
+++ b/dom/media/fmp4/wmf/WMFVideoMFTManager.cpp
@@ -508,7 +508,7 @@ WMFVideoMFTManager::Output(int64_t aStreamOffset,
     }
     // Else unexpected error, assert, and bail.
     NS_WARNING("WMFVideoMFTManager::Output() unexpected error");
-    return E_FAIL;
+    return hr;
   }
 
   nsRefPtr<VideoData> frame;
diff --git a/toolkit/components/telemetry/Histograms.json b/toolkit/components/telemetry/Histograms.json
index 77d9d16e0cfe..9b3bfdf12274 100644
--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -5561,6 +5561,12 @@
     "n_buckets": "1000",
     "description": "The time (in milliseconds) that it took a 'reconfigure thread' request to go round trip."
   },
+  "MEDIA_WMF_DECODE_ERROR": {
+    "expires_in_version": "50",
+    "kind": "enumerated",
+    "n_values": 256,
+    "description": "WMF media decoder error or success (0) codes."
+  },
   "VIDEO_CANPLAYTYPE_H264_CONSTRAINT_SET_FLAG": {
     "expires_in_version": "50",
     "kind": "enumerated",