diff --git a/dom/bindings/Bindings.conf b/dom/bindings/Bindings.conf
index 44ee4e71c739..5f86eb0a11eb 100644
--- a/dom/bindings/Bindings.conf
+++ b/dom/bindings/Bindings.conf
@@ -646,6 +646,10 @@ DOMInterfaces = {
     'headerFile': 'TransceiverImpl.h'
 },
 
+'TransformStreamDefaultController': {
+    'implicitJSContext': ['terminate'],
+},
+
 'Plugin': {
     'headerFile' : 'nsPluginArray.h',
     'nativeType': 'nsPluginElement',
diff --git a/dom/streams/ReadableStreamDefaultController.cpp b/dom/streams/ReadableStreamDefaultController.cpp
index 34a32c0503b3..0ac930fa907f 100644
--- a/dom/streams/ReadableStreamDefaultController.cpp
+++ b/dom/streams/ReadableStreamDefaultController.cpp
@@ -106,13 +106,11 @@ static bool ReadableStreamDefaultControllerCanCloseOrEnqueue(
          state == ReadableStream::ReaderState::Readable;
 }
 
-enum class CloseOrEnqueue { Close, Enqueue };
-
 // https://streams.spec.whatwg.org/#readable-stream-default-controller-can-close-or-enqueue
 // This is a variant of ReadableStreamDefaultControllerCanCloseOrEnqueue
 // that also throws when the function would return false to improve error
 // messages.
-static bool ReadableStreamDefaultControllerCanCloseOrEnqueueAndThrow(
+bool ReadableStreamDefaultControllerCanCloseOrEnqueueAndThrow(
     ReadableStreamDefaultController* aController,
     CloseOrEnqueue aCloseOrEnqueue, ErrorResult& aRv) {
   // Step 1. Let state be controller.[[stream]].[[state]].
@@ -120,9 +118,9 @@ static bool ReadableStreamDefaultControllerCanCloseOrEnqueueAndThrow(
 
   nsCString prefix;
   if (aCloseOrEnqueue == CloseOrEnqueue::Close) {
-    prefix = "Cannot close a readable stream that "_ns;
+    prefix = "Cannot close a stream that "_ns;
   } else {
-    prefix = "Cannot enqueue into a readable stream that "_ns;
+    prefix = "Cannot enqueue into a stream that "_ns;
   }
 
   switch (state) {
@@ -348,7 +346,7 @@ void ReadableStreamDefaultController::Error(JSContext* aCx,
 }
 
 // https://streams.spec.whatwg.org/#readable-stream-default-controller-should-call-pull
-static bool ReadableStreamDefaultControllerShouldCallPull(
+bool ReadableStreamDefaultControllerShouldCallPull(
     ReadableStreamDefaultController* aController) {
   // Step 1.
   ReadableStream* stream = aController->GetStream();
diff --git a/dom/streams/ReadableStreamDefaultController.h b/dom/streams/ReadableStreamDefaultController.h
index e76365f5fdb5..043507c2307d 100644
--- a/dom/streams/ReadableStreamDefaultController.h
+++ b/dom/streams/ReadableStreamDefaultController.h
@@ -159,6 +159,15 @@ void ReadableStreamDefaultControllerClearAlgorithms(
 Nullable<double> ReadableStreamDefaultControllerGetDesiredSize(
     ReadableStreamDefaultController* aController);
 
+enum class CloseOrEnqueue { Close, Enqueue };
+
+bool ReadableStreamDefaultControllerCanCloseOrEnqueueAndThrow(
+    ReadableStreamDefaultController* aController,
+    CloseOrEnqueue aCloseOrEnqueue, ErrorResult& aRv);
+
+bool ReadableStreamDefaultControllerShouldCallPull(
+    ReadableStreamDefaultController* aController);
+
 }  // namespace mozilla::dom
 
 #endif  // mozilla_dom_ReadableStreamDefaultController_h
diff --git a/dom/streams/TransformStream.cpp b/dom/streams/TransformStream.cpp
index 7270f63a7c3f..21ff0603dde8 100644
--- a/dom/streams/TransformStream.cpp
+++ b/dom/streams/TransformStream.cpp
@@ -40,6 +40,48 @@ JSObject* TransformStream::WrapObject(JSContext* aCx,
   return TransformStream_Binding::Wrap(aCx, this, aGivenProto);
 }
 
+// https://streams.spec.whatwg.org/#transform-stream-error-writable-and-unblock-write
+void TransformStreamErrorWritableAndUnblockWrite(JSContext* aCx,
+                                                 TransformStream* aStream,
+                                                 JS::HandleValue aError,
+                                                 ErrorResult& aRv) {
+  // Step 1: Perform !
+  // TransformStreamDefaultControllerClearAlgorithms(stream.[[controller]]).
+  aStream->Controller()->SetAlgorithms(nullptr);
+
+  // Step 2: Perform !
+  // WritableStreamDefaultControllerErrorIfNeeded(stream.[[writable]].[[controller]],
+  // e).
+  // TODO: Remove MOZ_KnownLive (bug 1761577)
+  WritableStreamDefaultControllerErrorIfNeeded(
+      aCx, MOZ_KnownLive(aStream->Writable()->Controller()), aError, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  // Step 3: If stream.[[backpressure]] is true, perform !
+  // TransformStreamSetBackpressure(stream, false).
+  if (aStream->Backpressure()) {
+    TransformStreamSetBackpressure(aStream, false, aRv);
+  }
+}
+
+// https://streams.spec.whatwg.org/#transform-stream-error
+void TransformStreamError(JSContext* aCx, TransformStream* aStream,
+                          JS::HandleValue aError, ErrorResult& aRv) {
+  // Step 1: Perform !
+  // ReadableStreamDefaultControllerError(stream.[[readable]].[[controller]],
+  // e).
+  ReadableStreamDefaultControllerError(
+      aCx, aStream->Readable()->Controller()->AsDefault(), aError, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  // Step 2: Perform ! TransformStreamErrorWritableAndUnblockWrite(stream, e).
+  TransformStreamErrorWritableAndUnblockWrite(aCx, aStream, aError, aRv);
+}
+
 // https://streams.spec.whatwg.org/#initialize-transform-stream
 class TransformStreamUnderlyingSinkAlgorithms final
     : public UnderlyingSinkAlgorithmsBase {
@@ -178,9 +220,8 @@ NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(
 NS_INTERFACE_MAP_END_INHERITING(TransformStreamUnderlyingSourceAlgorithms)
 
 // https://streams.spec.whatwg.org/#transform-stream-set-backpressure
-static void TransformStreamSetBackpressure(TransformStream* aStream,
-                                           bool aBackpressure,
-                                           ErrorResult& aRv) {
+void TransformStreamSetBackpressure(TransformStream* aStream,
+                                    bool aBackpressure, ErrorResult& aRv) {
   // Step 1. Assert: stream.[[backpressure]] is not backpressure.
   MOZ_ASSERT(aStream->Backpressure() != aBackpressure);
 
@@ -238,6 +279,11 @@ void TransformStream::Initialize(JSContext* aCx, Promise* aStartPromise,
 
   // Step 9. Set stream.[[backpressure]] and
   // stream.[[backpressureChangePromise]] to undefined.
+  // Note(krosylight): The spec allows setting [[backpressure]] as undefined,
+  // but I don't see why it should be. Since the spec also allows strict boolean
+  // type, and this is only to not trigger assertion inside the setter, we just
+  // set it as false.
+  mBackpressure = false;
   mBackpressureChangePromise = nullptr;
 
   // Step 10. Perform ! TransformStreamSetBackpressure(stream, true).
diff --git a/dom/streams/TransformStream.h b/dom/streams/TransformStream.h
index 2c9d7f4f0d58..4c565209278d 100644
--- a/dom/streams/TransformStream.h
+++ b/dom/streams/TransformStream.h
@@ -36,12 +36,15 @@ class TransformStream final : public nsISupports, public nsWrapperCache {
   void SetBackpressureChangePromise(Promise* aPromise) {
     mBackpressureChangePromise = aPromise;
   }
-  TransformStreamDefaultController* Controller() { return mController; }
-  void SetController(TransformStreamDefaultController* aController) {
-    mController = aController;
+  MOZ_KNOWN_LIVE TransformStreamDefaultController* Controller() {
+    return mController;
   }
-  ReadableStream* Readable() { return mReadable; }
-  WritableStream* Writable() { return mWritable; }
+  void SetController(TransformStreamDefaultController& aController) {
+    MOZ_ASSERT(!mController);
+    mController = &aController;
+  }
+  MOZ_KNOWN_LIVE ReadableStream* Readable() { return mReadable; }
+  MOZ_KNOWN_LIVE WritableStream* Writable() { return mWritable; }
 
  protected:
   ~TransformStream();
@@ -73,13 +76,26 @@ class TransformStream final : public nsISupports, public nsWrapperCache {
   nsCOMPtr<nsIGlobalObject> mGlobal;
 
   // Internal slots
+  // MOZ_KNOWN_LIVE for slots that will never be reassigned
   bool mBackpressure = false;
   RefPtr<Promise> mBackpressureChangePromise;
-  RefPtr<TransformStreamDefaultController> mController;
-  RefPtr<ReadableStream> mReadable;
-  RefPtr<WritableStream> mWritable;
+  MOZ_KNOWN_LIVE RefPtr<TransformStreamDefaultController> mController;
+  MOZ_KNOWN_LIVE RefPtr<ReadableStream> mReadable;
+  MOZ_KNOWN_LIVE RefPtr<WritableStream> mWritable;
 };
 
+MOZ_CAN_RUN_SCRIPT void TransformStreamErrorWritableAndUnblockWrite(
+    JSContext* aCx, TransformStream* aStream, JS::HandleValue aError,
+    ErrorResult& aRv);
+
+MOZ_CAN_RUN_SCRIPT void TransformStreamError(JSContext* aCx,
+                                             TransformStream* aStream,
+                                             JS::HandleValue aError,
+                                             ErrorResult& aRv);
+
+void TransformStreamSetBackpressure(TransformStream* aStream,
+                                    bool aBackpressure, ErrorResult& aRv);
+
 }  // namespace mozilla::dom
 
 #endif  // DOM_STREAMS_TRANSFORMSTREAM_H_
diff --git a/dom/streams/TransformStreamDefaultController.cpp b/dom/streams/TransformStreamDefaultController.cpp
index 7270e335d06e..ef6b4577c3dd 100644
--- a/dom/streams/TransformStreamDefaultController.cpp
+++ b/dom/streams/TransformStreamDefaultController.cpp
@@ -26,8 +26,9 @@ NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TransformStreamDefaultController)
   NS_INTERFACE_MAP_ENTRY(nsISupports)
 NS_INTERFACE_MAP_END
 
-void TransformStreamDefaultController::SetStream(TransformStream* aStream) {
-  mStream = aStream;
+void TransformStreamDefaultController::SetStream(TransformStream& aStream) {
+  MOZ_ASSERT(!mStream);
+  mStream = &aStream;
 }
 
 void TransformStreamDefaultController::SetAlgorithms(
@@ -62,20 +63,123 @@ Nullable<double> TransformStreamDefaultController::GetDesiredSize() const {
   return ReadableStreamDefaultControllerGetDesiredSize(readableController);
 }
 
+// https://streams.spec.whatwg.org/#rs-default-controller-has-backpressure
+// Looks like a readable stream thing but the spec explicitly says this is for
+// TransformStream.
+static bool ReadableStreamDefaultControllerHasBackpressure(
+    ReadableStreamDefaultController* aController) {
+  // Step 1: If ! ReadableStreamDefaultControllerShouldCallPull(controller) is
+  // true, return false.
+  // Step 2: Otherwise, return true.
+  return !ReadableStreamDefaultControllerShouldCallPull(aController);
+}
+
 void TransformStreamDefaultController::Enqueue(JSContext* aCx,
                                                JS::Handle<JS::Value> aChunk,
                                                ErrorResult& aRv) {
-  aRv.Throw(NS_ERROR_NOT_IMPLEMENTED);
+  // Step 1: Perform ? TransformStreamDefaultControllerEnqueue(this, chunk).
+
+  // Inlining TransformStreamDefaultControllerEnqueue here.
+  // https://streams.spec.whatwg.org/#transform-stream-default-controller-enqueue
+
+  // Step 1: Let stream be controller.[[stream]].
+  RefPtr<TransformStream> stream = mStream;
+
+  // Step 2: Let readableController be stream.[[readable]].[[controller]].
+  RefPtr<ReadableStreamDefaultController> readableController =
+      stream->Readable()->Controller()->AsDefault();
+
+  // Step 3: If !
+  // ReadableStreamDefaultControllerCanCloseOrEnqueue(readableController) is
+  // false, throw a TypeError exception.
+  if (!ReadableStreamDefaultControllerCanCloseOrEnqueueAndThrow(
+          readableController, CloseOrEnqueue::Enqueue, aRv)) {
+    return;
+  }
+
+  // Step 4: Let enqueueResult be
+  // ReadableStreamDefaultControllerEnqueue(readableController, chunk).
+  ErrorResult rv;
+  ReadableStreamDefaultControllerEnqueue(aCx, readableController, aChunk, rv);
+
+  // Step 5: If enqueueResult is an abrupt completion,
+  if (rv.MaybeSetPendingException(aCx)) {
+    JS::Rooted<JS::Value> error(aCx);
+    if (!JS_GetPendingException(aCx, &error)) {
+      // Uncatchable exception; we should mark aRv and return.
+      aRv.StealExceptionFromJSContext(aCx);
+      return;
+    }
+    JS_ClearPendingException(aCx);
+
+    // Step 5.1: Perform ! TransformStreamErrorWritableAndUnblockWrite(stream,
+    // enqueueResult.[[Value]]).
+    TransformStreamErrorWritableAndUnblockWrite(aCx, stream, error, aRv);
+
+    // Step 5.2: Throw stream.[[readable]].[[storedError]].
+    JS::RootedValue storedError(aCx, stream->Readable()->StoredError());
+    aRv.MightThrowJSException();
+    aRv.ThrowJSException(aCx, storedError);
+    return;
+  }
+
+  // Step 6: Let backpressure be !
+  // ReadableStreamDefaultControllerHasBackpressure(readableController).
+  bool backpressure =
+      ReadableStreamDefaultControllerHasBackpressure(readableController);
+
+  // Step 7: If backpressure is not stream.[[backpressure]],
+  if (backpressure != stream->Backpressure()) {
+    // Step 7.1: Assert: backpressure is true.
+    MOZ_ASSERT(backpressure);
+
+    // Step 7.2: Perform ! TransformStreamSetBackpressure(stream, true).
+    TransformStreamSetBackpressure(stream, true, aRv);
+  }
 }
 
+// https://streams.spec.whatwg.org/#ts-default-controller-error
 void TransformStreamDefaultController::Error(JSContext* aCx,
                                              JS::Handle<JS::Value> aError,
                                              ErrorResult& aRv) {
-  aRv.Throw(NS_ERROR_NOT_IMPLEMENTED);
+  // Step 1: Perform ? TransformStreamDefaultControllerError(this, e).
+
+  // Inlining TransformStreamDefaultControllerError here.
+  // https://streams.spec.whatwg.org/#transform-stream-default-controller-error
+
+  // Perform ! TransformStreamError(controller.[[stream]], e).
+  TransformStreamError(aCx, mStream, aError, aRv);
 }
 
-void TransformStreamDefaultController::Terminate(ErrorResult& aRv) {
-  aRv.Throw(NS_ERROR_NOT_IMPLEMENTED);
+// https://streams.spec.whatwg.org/#ts-default-controller-terminate
+
+void TransformStreamDefaultController::Terminate(JSContext* aCx,
+                                                 ErrorResult& aRv) {
+  // Step 1: Perform ? TransformStreamDefaultControllerTerminate(this).
+
+  // Inlining TransformStreamDefaultControllerTerminate here.
+  // https://streams.spec.whatwg.org/#transform-stream-default-controller-terminate
+
+  // Step 1: Let stream be controller.[[stream]].
+  RefPtr<TransformStream> stream = mStream;
+
+  // Step 2: Let readableController be stream.[[readable]].[[controller]].
+  RefPtr<ReadableStreamDefaultController> readableController =
+      stream->Readable()->Controller()->AsDefault();
+
+  // Step 3: Perform ! ReadableStreamDefaultControllerClose(readableController).
+  ReadableStreamDefaultControllerClose(aCx, readableController, aRv);
+
+  // Step 4: Let error be a TypeError exception indicating that the stream has
+  // been terminated.
+  ErrorResult rv;
+  rv.ThrowTypeError("Terminating the stream");
+  JS::Rooted<JS::Value> error(aCx);
+  MOZ_ALWAYS_TRUE(ToJSValue(aCx, std::move(rv), &error));
+
+  // Step 5: Perform ! TransformStreamErrorWritableAndUnblockWrite(stream,
+  // error).
+  TransformStreamErrorWritableAndUnblockWrite(aCx, stream, error, aRv);
 }
 
 // https://streams.spec.whatwg.org/#set-up-transform-stream-default-controller
@@ -88,10 +192,10 @@ void SetUpTransformStreamDefaultController(
   MOZ_ASSERT(!aStream.Controller());
 
   // Step 3. Set controller.[[stream]] to stream.
-  aController.SetStream(&aStream);
+  aController.SetStream(aStream);
 
   // Step 4. Set stream.[[controller]] to controller.
-  aStream.SetController(&aController);
+  aStream.SetController(aController);
 
   // Step 5. Set controller.[[transformAlgorithm]] to transformAlgorithm.
   // Step 6. Set controller.[[flushAlgorithm]] to flushAlgorithm.
diff --git a/dom/streams/TransformStreamDefaultController.h b/dom/streams/TransformStreamDefaultController.h
index 07016d549c13..701a735b9d66 100644
--- a/dom/streams/TransformStreamDefaultController.h
+++ b/dom/streams/TransformStreamDefaultController.h
@@ -31,7 +31,7 @@ class TransformStreamDefaultController final : public nsISupports,
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(TransformStreamDefaultController)
 
-  void SetStream(TransformStream* aStream);
+  void SetStream(TransformStream& aStream);
   void SetAlgorithms(TransformerAlgorithms* aTransformerAlgorithms);
 
   explicit TransformStreamDefaultController(nsIGlobalObject* aGlobal);
@@ -46,15 +46,17 @@ class TransformStreamDefaultController final : public nsISupports,
 
   Nullable<double> GetDesiredSize() const;
 
-  void Enqueue(JSContext* aCx, JS::Handle<JS::Value> aChunk, ErrorResult& aRv);
-  void Error(JSContext* aCx, JS::Handle<JS::Value> aError, ErrorResult& aRv);
-  void Terminate(ErrorResult& aRv);
+  MOZ_CAN_RUN_SCRIPT void Enqueue(JSContext* aCx, JS::Handle<JS::Value> aChunk,
+                                  ErrorResult& aRv);
+  MOZ_CAN_RUN_SCRIPT void Error(JSContext* aCx, JS::Handle<JS::Value> aError,
+                                ErrorResult& aRv);
+  MOZ_CAN_RUN_SCRIPT void Terminate(JSContext* aCx, ErrorResult& aRv);
 
  private:
   nsCOMPtr<nsIGlobalObject> mGlobal;
 
   // Internal slots
-  RefPtr<TransformStream> mStream;
+  MOZ_KNOWN_LIVE RefPtr<TransformStream> mStream;
   RefPtr<TransformerAlgorithms> mTransformerAlgorithms;
 };
 
diff --git a/dom/streams/WritableStream.h b/dom/streams/WritableStream.h
index 4700a819f595..ce19326fdf58 100644
--- a/dom/streams/WritableStream.h
+++ b/dom/streams/WritableStream.h
@@ -52,10 +52,12 @@ class WritableStream : public nsISupports, public nsWrapperCache {
   Promise* GetCloseRequest() { return mCloseRequest; }
   void SetCloseRequest(Promise* aRequest) { mCloseRequest = aRequest; }
 
-  WritableStreamDefaultController* Controller() { return mController; }
-  void SetController(WritableStreamDefaultController* aController) {
-    MOZ_ASSERT(aController);
-    mController = aController;
+  MOZ_KNOWN_LIVE WritableStreamDefaultController* Controller() {
+    return mController;
+  }
+  void SetController(WritableStreamDefaultController& aController) {
+    MOZ_ASSERT(!mController);
+    mController = &aController;
   }
 
   Promise* GetInFlightWriteRequest() const { return mInFlightWriteRequest; }
@@ -162,7 +164,7 @@ class WritableStream : public nsISupports, public nsWrapperCache {
  private:
   bool mBackpressure = false;
   RefPtr<Promise> mCloseRequest;
-  RefPtr<WritableStreamDefaultController> mController;
+  MOZ_KNOWN_LIVE RefPtr<WritableStreamDefaultController> mController;
   RefPtr<Promise> mInFlightWriteRequest;
   RefPtr<Promise> mInFlightCloseRequest;
 
diff --git a/dom/streams/WritableStreamDefaultController.cpp b/dom/streams/WritableStreamDefaultController.cpp
index 8df09749c53b..38008a9b9c35 100644
--- a/dom/streams/WritableStreamDefaultController.cpp
+++ b/dom/streams/WritableStreamDefaultController.cpp
@@ -138,7 +138,7 @@ void SetUpWritableStreamDefaultController(
   MOZ_ASSERT(aController->Stream() == aStream);
 
   // Step 4. Set stream.[[controller]] to controller.
-  aStream->SetController(aController);
+  aStream->SetController(*aController);
 
   // Step 5. Perform ! ResetQueue(controller).
   ResetQueue(aController);
diff --git a/testing/web-platform/meta/streams/transform-streams/errors.any.js.ini b/testing/web-platform/meta/streams/transform-streams/errors.any.js.ini
index c4152600e888..16abd902dbd2 100644
--- a/testing/web-platform/meta/streams/transform-streams/errors.any.js.ini
+++ b/testing/web-platform/meta/streams/transform-streams/errors.any.js.ini
@@ -11,12 +11,6 @@
   [when controller.error is followed by a rejection, the error reason should come from controller.error]
     expected: FAIL
 
-  [when strategy.size throws inside start(), the constructor should throw the same error]
-    expected: FAIL
-
-  [when strategy.size calls controller.error() then throws, the constructor should throw the first error]
-    expected: FAIL
-
   [cancelling the readable side should error the writable]
     expected: FAIL
 
@@ -53,9 +47,6 @@
   [the readable should be errored with the reason passed to the writable abort() method]
     expected: FAIL
 
-  [errored TransformStream should not enqueue new chunks]
-    expected: FAIL
-
 
 [errors.any.serviceworker.html]
   [TransformStream errors thrown in transform put the writable and readable in an errored state]
@@ -70,12 +61,6 @@
   [when controller.error is followed by a rejection, the error reason should come from controller.error]
     expected: FAIL
 
-  [when strategy.size throws inside start(), the constructor should throw the same error]
-    expected: FAIL
-
-  [when strategy.size calls controller.error() then throws, the constructor should throw the first error]
-    expected: FAIL
-
   [cancelling the readable side should error the writable]
     expected: FAIL
 
@@ -112,9 +97,6 @@
   [the readable should be errored with the reason passed to the writable abort() method]
     expected: FAIL
 
-  [errored TransformStream should not enqueue new chunks]
-    expected: FAIL
-
 
 [errors.any.worker.html]
   [TransformStream errors thrown in transform put the writable and readable in an errored state]
@@ -129,12 +111,6 @@
   [when controller.error is followed by a rejection, the error reason should come from controller.error]
     expected: FAIL
 
-  [when strategy.size throws inside start(), the constructor should throw the same error]
-    expected: FAIL
-
-  [when strategy.size calls controller.error() then throws, the constructor should throw the first error]
-    expected: FAIL
-
   [cancelling the readable side should error the writable]
     expected: FAIL
 
@@ -171,9 +147,6 @@
   [the readable should be errored with the reason passed to the writable abort() method]
     expected: FAIL
 
-  [errored TransformStream should not enqueue new chunks]
-    expected: FAIL
-
 
 [errors.any.html]
   [TransformStream errors thrown in transform put the writable and readable in an errored state]
@@ -188,12 +161,6 @@
   [when controller.error is followed by a rejection, the error reason should come from controller.error]
     expected: FAIL
 
-  [when strategy.size throws inside start(), the constructor should throw the same error]
-    expected: FAIL
-
-  [when strategy.size calls controller.error() then throws, the constructor should throw the first error]
-    expected: FAIL
-
   [cancelling the readable side should error the writable]
     expected: FAIL
 
@@ -229,6 +196,3 @@
 
   [the readable should be errored with the reason passed to the writable abort() method]
     expected: FAIL
-
-  [errored TransformStream should not enqueue new chunks]
-    expected: FAIL
diff --git a/testing/web-platform/meta/streams/transform-streams/general.any.js.ini b/testing/web-platform/meta/streams/transform-streams/general.any.js.ini
index 0b163c08e560..255b45933b45 100644
--- a/testing/web-platform/meta/streams/transform-streams/general.any.js.ini
+++ b/testing/web-platform/meta/streams/transform-streams/general.any.js.ini
@@ -53,12 +53,6 @@
   [Subclassing TransformStream should work]
     expected: FAIL
 
-  [enqueue() should throw after controller.terminate()]
-    expected: FAIL
-
-  [controller.terminate() should do nothing the second time it is called]
-    expected: FAIL
-
 
 [general.any.html]
   [TransformStream writable starts in the writable state]
@@ -115,12 +109,6 @@
   [Subclassing TransformStream should work]
     expected: FAIL
 
-  [enqueue() should throw after controller.terminate()]
-    expected: FAIL
-
-  [controller.terminate() should do nothing the second time it is called]
-    expected: FAIL
-
 
 [general.any.worker.html]
   [TransformStream writable starts in the writable state]
@@ -177,12 +165,6 @@
   [Subclassing TransformStream should work]
     expected: FAIL
 
-  [enqueue() should throw after controller.terminate()]
-    expected: FAIL
-
-  [controller.terminate() should do nothing the second time it is called]
-    expected: FAIL
-
 
 [general.any.serviceworker.html]
   [TransformStream writable starts in the writable state]
@@ -238,9 +220,3 @@
 
   [Subclassing TransformStream should work]
     expected: FAIL
-
-  [enqueue() should throw after controller.terminate()]
-    expected: FAIL
-
-  [controller.terminate() should do nothing the second time it is called]
-    expected: FAIL
diff --git a/testing/web-platform/meta/streams/transform-streams/terminate.any.js.ini b/testing/web-platform/meta/streams/transform-streams/terminate.any.js.ini
index 7536f29dea2b..cf1b68ddbf43 100644
--- a/testing/web-platform/meta/streams/transform-streams/terminate.any.js.ini
+++ b/testing/web-platform/meta/streams/transform-streams/terminate.any.js.ini
@@ -14,9 +14,6 @@
   [controller.terminate() inside flush() should not prevent writer.close() from succeeding]
     expected: FAIL
 
-  [controller.enqueue() should throw after controller.terminate()]
-    expected: FAIL
-
 
 [terminate.any.worker.html]
   [controller.terminate() should error pipeTo()]
@@ -34,9 +31,6 @@
   [controller.terminate() inside flush() should not prevent writer.close() from succeeding]
     expected: FAIL
 
-  [controller.enqueue() should throw after controller.terminate()]
-    expected: FAIL
-
 
 [terminate.any.serviceworker.html]
   [controller.terminate() should error pipeTo()]
@@ -54,9 +48,6 @@
   [controller.terminate() inside flush() should not prevent writer.close() from succeeding]
     expected: FAIL
 
-  [controller.enqueue() should throw after controller.terminate()]
-    expected: FAIL
-
 
 [terminate.any.html]
   [controller.terminate() should error pipeTo()]
@@ -73,6 +64,3 @@
 
   [controller.terminate() inside flush() should not prevent writer.close() from succeeding]
     expected: FAIL
-
-  [controller.enqueue() should throw after controller.terminate()]
-    expected: FAIL