diff --git a/engine/updategraph/src/main/java/io/deephaven/engine/updategraph/UpdateGraphAwareCompletableFuture.java b/engine/updategraph/src/main/java/io/deephaven/engine/updategraph/UpdateGraphAwareCompletableFuture.java
index 7692c80a35b..1cf8d0cc36f 100644
--- a/engine/updategraph/src/main/java/io/deephaven/engine/updategraph/UpdateGraphAwareCompletableFuture.java
+++ b/engine/updategraph/src/main/java/io/deephaven/engine/updategraph/UpdateGraphAwareCompletableFuture.java
@@ -7,6 +7,7 @@
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.Objects;
 import java.util.concurrent.*;
 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
 import java.util.concurrent.locks.Condition;
@@ -57,6 +58,8 @@ public boolean isDone() {
 
     @Override
     public T get() throws InterruptedException, ExecutionException {
+        checkSharedLockState();
+
         if (resultSupplier != null) {
             return resultSupplier.get();
         }
@@ -70,6 +73,8 @@ public T get() throws InterruptedException, ExecutionException {
     @Override
     public T get(final long timeout, @NotNull final TimeUnit unit)
             throws InterruptedException, ExecutionException, TimeoutException {
+        checkSharedLockState();
+
         if (resultSupplier != null) {
             return resultSupplier.get();
         }
@@ -81,12 +86,6 @@ public T get(final long timeout, @NotNull final TimeUnit unit)
 
     private T getInternal(final long timeout, @Nullable final TimeUnit unit)
             throws InterruptedException, ExecutionException, TimeoutException {
-        // test lock conditions
-        if (updateGraph.sharedLock().isHeldByCurrentThread()) {
-            throw new UnsupportedOperationException(
-                    "Cannot Future.get(...) while holding the " + updateGraph + " shared lock");
-        }
-
         final boolean holdingUpdateGraphLock = updateGraph.exclusiveLock().isHeldByCurrentThread();
         if (holdingUpdateGraphLock) {
             if (updateGraphCondition == null) {
@@ -111,6 +110,13 @@ private T getInternal(final long timeout, @Nullable final TimeUnit unit)
         return resultSupplier.get();
     }
 
+    private void checkSharedLockState() {
+        if (updateGraph.sharedLock().isHeldByCurrentThread()) {
+            throw new UnsupportedOperationException(
+                    "Cannot Future.get(...) while holding the " + updateGraph + " shared lock");
+        }
+    }
+
     private void waitForResult(final Condition condition, final long timeout, @Nullable final TimeUnit unit)
             throws InterruptedException, TimeoutException {
         if (unit == null) {
@@ -138,9 +144,7 @@ public boolean complete(T value) {
     }
 
     public boolean completeExceptionally(Throwable ex) {
-        if (ex == null) {
-            throw new NullPointerException();
-        }
+        Objects.requireNonNull(ex);
         return trySignalCompletion(() -> {
             throw new ExecutionException(ex);
         });
diff --git a/java-client/barrage/src/main/java/io/deephaven/client/impl/BarrageSubscriptionImpl.java b/java-client/barrage/src/main/java/io/deephaven/client/impl/BarrageSubscriptionImpl.java
index 653a2c367f7..5d1a0006e43 100644
--- a/java-client/barrage/src/main/java/io/deephaven/client/impl/BarrageSubscriptionImpl.java
+++ b/java-client/barrage/src/main/java/io/deephaven/client/impl/BarrageSubscriptionImpl.java
@@ -250,8 +250,9 @@ private void onFutureComplete() {
     protected void destroy() {
         super.destroy();
         cancel("no longer live");
-        if (future != null) {
-            future.completeExceptionally(new RequestCancelledException("Barrage subscription is no longer live"));
+        final FutureAdapter localFuture = future;
+        if (localFuture != null) {
+            localFuture.completeExceptionally(new RequestCancelledException("Barrage subscription is no longer live"));
         }
     }
 
diff --git a/server/src/main/java/io/deephaven/server/arrow/ArrowFlightUtil.java b/server/src/main/java/io/deephaven/server/arrow/ArrowFlightUtil.java
index 789581ff3c0..c2351dfeae2 100644
--- a/server/src/main/java/io/deephaven/server/arrow/ArrowFlightUtil.java
+++ b/server/src/main/java/io/deephaven/server/arrow/ArrowFlightUtil.java
@@ -658,6 +658,12 @@ private synchronized void onExportResolved(final SessionState.ExportObject<Objec
                 final Object export = parent.get();
                 if (export instanceof QueryTable) {
                     final QueryTable table = (QueryTable) export;
+
+                    if (table.isFailed()) {
+                        throw Exceptions.statusRuntimeException(Code.FAILED_PRECONDITION,
+                                "Table is already failed");
+                    }
+
                     final UpdateGraph ug = table.getUpdateGraph();
                     try (final SafeCloseable ignored = ExecutionContext.getContext().withUpdateGraph(ug).open()) {
                         bmp = table.getResult(bmpOperationFactory.create(table, minUpdateIntervalMs));