diff --git a/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/ResettableThrowingStreamObserver.java b/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/ResettableThrowingStreamObserver.java
index 1e197c877d68..b027a6cac7b0 100644
--- a/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/ResettableThrowingStreamObserver.java
+++ b/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/ResettableThrowingStreamObserver.java
@@ -115,14 +115,24 @@ public void onNext(T t) throws StreamClosedException, WindmillStreamShutdownExce
           logger.debug("Stream was shutdown during send.", cancellationException);
           return;
         }
+        if (delegateStreamObserver == delegate) {
+          if (isCurrentStreamClosed) {
+            logger.debug("Stream is already closed when encountering error with send.");
+            return;
+          }
+          isCurrentStreamClosed = true;
+        }
       }
 
+      // Either this was the active observer the current observer that requires closing, or this was
+      // a previous
+      // observer which we attempt to close and ignore possible exceptions.
       try {
         delegate.onError(cancellationException);
       } catch (IllegalStateException onErrorException) {
         // The delegate above was already terminated via onError or onComplete.
-        // Fallthrough since this is possibly due to queued onNext() calls that are being made from
-        // previously blocked threads.
+        // Fallthrough since this is possibly due to queued onNext() calls that are being made
+        // from previously blocked threads.
       } catch (RuntimeException onErrorException) {
         logger.warn(
             "Encountered unexpected error {} when cancelling due to error.",
@@ -134,14 +144,20 @@ public void onNext(T t) throws StreamClosedException, WindmillStreamShutdownExce
 
   public synchronized void onError(Throwable throwable)
       throws StreamClosedException, WindmillStreamShutdownException {
-    delegate().onError(throwable);
-    isCurrentStreamClosed = true;
+    try {
+      delegate().onError(throwable);
+    } finally {
+      isCurrentStreamClosed = true;
+    }
   }
 
   public synchronized void onCompleted()
       throws StreamClosedException, WindmillStreamShutdownException {
-    delegate().onCompleted();
-    isCurrentStreamClosed = true;
+    try {
+      delegate().onCompleted();
+    } finally {
+      isCurrentStreamClosed = true;
+    }
   }
 
   synchronized boolean isClosed() {
diff --git a/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/grpc/observers/DirectStreamObserver.java b/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/grpc/observers/DirectStreamObserver.java
index 173cbd26c4e7..bf060bd6acfe 100644
--- a/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/grpc/observers/DirectStreamObserver.java
+++ b/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/grpc/observers/DirectStreamObserver.java
@@ -182,8 +182,8 @@ public void onError(Throwable t) {
       Preconditions.checkState(!isUserClosed);
       isUserClosed = true;
       if (!isOutboundObserverClosed) {
-        outboundObserver.onError(t);
         isOutboundObserverClosed = true;
+        outboundObserver.onError(t);
       }
     }
   }
diff --git a/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/grpc/observers/StreamObserverCancelledException.java b/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/grpc/observers/StreamObserverCancelledException.java
index 70fd3497a37f..5682d5085d2b 100644
--- a/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/grpc/observers/StreamObserverCancelledException.java
+++ b/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/grpc/observers/StreamObserverCancelledException.java
@@ -21,15 +21,15 @@
 
 @Internal
 public final class StreamObserverCancelledException extends RuntimeException {
-  StreamObserverCancelledException(Throwable cause) {
+  public StreamObserverCancelledException(Throwable cause) {
     super(cause);
   }
 
-  StreamObserverCancelledException(String message, Throwable cause) {
+  public StreamObserverCancelledException(String message, Throwable cause) {
     super(message, cause);
   }
 
-  StreamObserverCancelledException(String message) {
+  public StreamObserverCancelledException(String message) {
     super(message);
   }
 }
diff --git a/runners/google-cloud-dataflow-java/worker/src/test/java/org/apache/beam/runners/dataflow/worker/windmill/client/ResettableThrowingStreamObserverTest.java b/runners/google-cloud-dataflow-java/worker/src/test/java/org/apache/beam/runners/dataflow/worker/windmill/client/ResettableThrowingStreamObserverTest.java
index ef7a865748dd..69c54a50b574 100644
--- a/runners/google-cloud-dataflow-java/worker/src/test/java/org/apache/beam/runners/dataflow/worker/windmill/client/ResettableThrowingStreamObserverTest.java
+++ b/runners/google-cloud-dataflow-java/worker/src/test/java/org/apache/beam/runners/dataflow/worker/windmill/client/ResettableThrowingStreamObserverTest.java
@@ -18,12 +18,15 @@
 package org.apache.beam.runners.dataflow.worker.windmill.client;
 
 import static org.junit.Assert.assertThrows;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.ArgumentMatchers.isA;
+import static org.mockito.Mockito.doThrow;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoInteractions;
 
+import org.apache.beam.runners.dataflow.worker.windmill.client.grpc.observers.StreamObserverCancelledException;
 import org.apache.beam.runners.dataflow.worker.windmill.client.grpc.observers.TerminatingStreamObserver;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -51,6 +54,53 @@ public void terminate(Throwable terminationException) {}
         });
   }
 
+  @Test
+  public void testOnNext_simple() throws Exception {
+    ResettableThrowingStreamObserver<Integer> observer = newStreamObserver();
+    TerminatingStreamObserver<Integer> spiedDelegate = newDelegate();
+    observer.reset(spiedDelegate);
+    observer.onNext(1);
+    verify(spiedDelegate).onNext(eq(1));
+    observer.onNext(2);
+    verify(spiedDelegate).onNext(eq(2));
+    observer.onCompleted();
+    verify(spiedDelegate).onCompleted();
+  }
+
+  @Test
+  public void testOnError_success() throws Exception {
+    ResettableThrowingStreamObserver<Integer> observer = newStreamObserver();
+    TerminatingStreamObserver<Integer> spiedDelegate = newDelegate();
+    observer.reset(spiedDelegate);
+    Throwable t = new RuntimeException("Test exception");
+    observer.onError(t);
+    verify(spiedDelegate).onError(eq(t));
+
+    assertThrows(
+        ResettableThrowingStreamObserver.StreamClosedException.class, () -> observer.onNext(1));
+    assertThrows(
+        ResettableThrowingStreamObserver.StreamClosedException.class, observer::onCompleted);
+    assertThrows(
+        ResettableThrowingStreamObserver.StreamClosedException.class,
+        () -> observer.onError(new RuntimeException("ignored")));
+  }
+
+  @Test
+  public void testOnCompleted_success() throws Exception {
+    ResettableThrowingStreamObserver<Integer> observer = newStreamObserver();
+    TerminatingStreamObserver<Integer> spiedDelegate = newDelegate();
+    observer.reset(spiedDelegate);
+    observer.onCompleted();
+    verify(spiedDelegate).onCompleted();
+    assertThrows(
+        ResettableThrowingStreamObserver.StreamClosedException.class, () -> observer.onNext(1));
+    assertThrows(
+        ResettableThrowingStreamObserver.StreamClosedException.class, observer::onCompleted);
+    assertThrows(
+        ResettableThrowingStreamObserver.StreamClosedException.class,
+        () -> observer.onError(new RuntimeException("ignored")));
+  }
+
   @Test
   public void testPoison_beforeDelegateSet() {
     ResettableThrowingStreamObserver<Integer> observer = newStreamObserver();
@@ -97,9 +147,7 @@ public void testOnCompleted_afterPoisonedThrows() {
   }
 
   @Test
-  public void testReset_usesNewDelegate()
-      throws WindmillStreamShutdownException,
-          ResettableThrowingStreamObserver.StreamClosedException {
+  public void testReset_usesNewDelegate() throws Exception {
     ResettableThrowingStreamObserver<Integer> observer = newStreamObserver();
     TerminatingStreamObserver<Integer> firstObserver = newDelegate();
     observer.reset(firstObserver);
@@ -113,6 +161,24 @@ public void testReset_usesNewDelegate()
     verify(secondObserver).onNext(eq(2));
   }
 
+  @Test
+  public void testOnNext_streamCancelledException_closesStream() throws Exception {
+    ResettableThrowingStreamObserver<Integer> observer = newStreamObserver();
+    TerminatingStreamObserver<Integer> spiedDelegate = newDelegate();
+    StreamObserverCancelledException streamObserverCancelledException =
+        new StreamObserverCancelledException("Test error");
+    doThrow(streamObserverCancelledException).when(spiedDelegate).onNext(any());
+    observer.reset(spiedDelegate);
+    observer.onNext(1);
+
+    verify(spiedDelegate).onError(eq(streamObserverCancelledException));
+    assertThrows(
+        ResettableThrowingStreamObserver.StreamClosedException.class,
+        () -> observer.onError(new Exception()));
+    assertThrows(
+        ResettableThrowingStreamObserver.StreamClosedException.class, observer::onCompleted);
+  }
+
   private <T> ResettableThrowingStreamObserver<T> newStreamObserver() {
     return new ResettableThrowingStreamObserver<>(LoggerFactory.getLogger(getClass()));
   }