diff --git a/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/StreamingDataflowWorker.java b/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/StreamingDataflowWorker.java
index c49865aa7511..a683ff1e748d 100644
--- a/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/StreamingDataflowWorker.java
+++ b/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/StreamingDataflowWorker.java
@@ -848,7 +848,11 @@ public void run() {
           new TimerTask() {
             @Override
             public void run() {
-              refreshActiveWork();
+              try {
+                refreshActiveWork();
+              } catch (RuntimeException e) {
+                LOG.warn("Failed to refresh active work: ", e);
+              }
             }
           },
           options.getActiveWorkRefreshPeriodMillis(),
diff --git a/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/GrpcWindmillServer.java b/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/GrpcWindmillServer.java
index 781ee596708a..6631ffa13e8a 100644
--- a/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/GrpcWindmillServer.java
+++ b/runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/GrpcWindmillServer.java
@@ -663,6 +663,9 @@ protected AbstractWindmillStream(
     protected final void send(RequestT request) {
       lastSendTimeMs.set(Instant.now().getMillis());
       synchronized (this) {
+        if (clientClosed.get()) {
+          throw new IllegalStateException("Send called on a client closed stream.");
+        }
         requestObserver.onNext(request);
       }
     }