diff --git a/server/src/test/java/org/opensearch/cluster/routing/allocation/allocator/TimeBoundBalancedShardsAllocatorTests.java b/server/src/test/java/org/opensearch/cluster/routing/allocation/allocator/TimeBoundBalancedShardsAllocatorTests.java
index ee50074bd9f5c..45a0bd7b18afd 100644
--- a/server/src/test/java/org/opensearch/cluster/routing/allocation/allocator/TimeBoundBalancedShardsAllocatorTests.java
+++ b/server/src/test/java/org/opensearch/cluster/routing/allocation/allocator/TimeBoundBalancedShardsAllocatorTests.java
@@ -8,6 +8,7 @@
 
 package org.opensearch.cluster.routing.allocation.allocator;
 
+import org.opensearch.OpenSearchException;
 import org.opensearch.Version;
 import org.opensearch.cluster.ClusterInfo;
 import org.opensearch.cluster.ClusterName;
@@ -101,7 +102,11 @@ public void testAllUnassignedShardsAllocatedWhenNoTimeOutAndRerouteNotScheduled(
         );
         AtomicBoolean rerouteScheduled = new AtomicBoolean(false);
         final RerouteService rerouteService = (reason, priority, listener) -> {
-            listener.onResponse(clusterService.state());
+            if (randomBoolean()) {
+                listener.onFailure(new OpenSearchException("simulated"));
+            } else {
+                listener.onResponse(clusterService.state());
+            }
             assertEquals("reroute after balanced shards allocator timed out", reason);
             assertEquals(Priority.HIGH, priority);
             rerouteScheduled.compareAndSet(false, true);
@@ -139,7 +144,11 @@ public void testAllUnassignedShardsIgnoredWhenTimedOutAndRerouteScheduled() {
         );
         AtomicBoolean rerouteScheduled = new AtomicBoolean(false);
         final RerouteService rerouteService = (reason, priority, listener) -> {
-            listener.onResponse(clusterService.state());
+            if (randomBoolean()) {
+                listener.onFailure(new OpenSearchException("simulated"));
+            } else {
+                listener.onResponse(clusterService.state());
+            }
             assertEquals("reroute after balanced shards allocator timed out", reason);
             assertEquals(Priority.HIGH, priority);
             rerouteScheduled.compareAndSet(false, true);
@@ -178,7 +187,11 @@ public void testAllocatePartialPrimaryShardsUntilTimedOutAndRerouteScheduled() {
         );
         AtomicBoolean rerouteScheduled = new AtomicBoolean(false);
         final RerouteService rerouteService = (reason, priority, listener) -> {
-            listener.onResponse(clusterService.state());
+            if (randomBoolean()) {
+                listener.onFailure(new OpenSearchException("simulated"));
+            } else {
+                listener.onResponse(clusterService.state());
+            }
             assertEquals("reroute after balanced shards allocator timed out", reason);
             assertEquals(Priority.HIGH, priority);
             rerouteScheduled.compareAndSet(false, true);
@@ -218,7 +231,11 @@ public void testAllocateAllPrimaryShardsAndPartialReplicaShardsUntilTimedOutAndR
         );
         AtomicBoolean rerouteScheduled = new AtomicBoolean(false);
         final RerouteService rerouteService = (reason, priority, listener) -> {
-            listener.onResponse(clusterService.state());
+            if (randomBoolean()) {
+                listener.onFailure(new OpenSearchException("simulated"));
+            } else {
+                listener.onResponse(clusterService.state());
+            }
             assertEquals("reroute after balanced shards allocator timed out", reason);
             assertEquals(Priority.HIGH, priority);
             rerouteScheduled.compareAndSet(false, true);
@@ -261,7 +278,11 @@ public void testAllShardsMoveWhenExcludedAndTimeoutNotBreachedAndRerouteNotSched
         );
         AtomicBoolean rerouteScheduled = new AtomicBoolean(false);
         final RerouteService rerouteService = (reason, priority, listener) -> {
-            listener.onResponse(clusterService.state());
+            if (randomBoolean()) {
+                listener.onFailure(new OpenSearchException("simulated"));
+            } else {
+                listener.onResponse(clusterService.state());
+            }
             assertEquals("reroute after balanced shards allocator timed out", reason);
             assertEquals(Priority.HIGH, priority);
             rerouteScheduled.compareAndSet(false, true);
@@ -299,7 +320,11 @@ public void testNoShardsMoveWhenExcludedAndTimeoutBreachedAndRerouteScheduled()
         );
         AtomicBoolean rerouteScheduled = new AtomicBoolean(false);
         final RerouteService rerouteService = (reason, priority, listener) -> {
-            listener.onResponse(clusterService.state());
+            if (randomBoolean()) {
+                listener.onFailure(new OpenSearchException("simulated"));
+            } else {
+                listener.onResponse(clusterService.state());
+            }
             assertEquals("reroute after balanced shards allocator timed out", reason);
             assertEquals(Priority.HIGH, priority);
             rerouteScheduled.compareAndSet(false, true);
@@ -340,7 +365,11 @@ public void testPartialShardsMoveWhenExcludedAndTimeoutBreachedAndRerouteSchedul
         );
         AtomicBoolean rerouteScheduled = new AtomicBoolean(false);
         final RerouteService rerouteService = (reason, priority, listener) -> {
-            listener.onResponse(clusterService.state());
+            if (randomBoolean()) {
+                listener.onFailure(new OpenSearchException("simulated"));
+            } else {
+                listener.onResponse(clusterService.state());
+            }
             assertEquals("reroute after balanced shards allocator timed out", reason);
             assertEquals(Priority.HIGH, priority);
             rerouteScheduled.compareAndSet(false, true);
@@ -381,7 +410,11 @@ public void testClusterRebalancedWhenNotTimedOutAndRerouteNotScheduled() {
         );
         AtomicBoolean rerouteScheduled = new AtomicBoolean(false);
         final RerouteService rerouteService = (reason, priority, listener) -> {
-            listener.onResponse(clusterService.state());
+            if (randomBoolean()) {
+                listener.onFailure(new OpenSearchException("simulated"));
+            } else {
+                listener.onResponse(clusterService.state());
+            }
             assertEquals("reroute after balanced shards allocator timed out", reason);
             assertEquals(Priority.HIGH, priority);
             rerouteScheduled.compareAndSet(false, true);
@@ -423,7 +456,11 @@ public void testClusterNotRebalancedWhenTimedOutAndRerouteScheduled() {
         );
         AtomicBoolean rerouteScheduled = new AtomicBoolean(false);
         final RerouteService rerouteService = (reason, priority, listener) -> {
-            listener.onResponse(clusterService.state());
+            if (randomBoolean()) {
+                listener.onFailure(new OpenSearchException("simulated"));
+            } else {
+                listener.onResponse(clusterService.state());
+            }
             assertEquals("reroute after balanced shards allocator timed out", reason);
             assertEquals(Priority.HIGH, priority);
             rerouteScheduled.compareAndSet(false, true);
@@ -479,7 +516,11 @@ public Decision canRebalance(ShardRouting shardRouting, RoutingAllocation alloca
         );
         AtomicBoolean rerouteScheduled = new AtomicBoolean(false);
         final RerouteService rerouteService = (reason, priority, listener) -> {
-            listener.onResponse(clusterService.state());
+            if (randomBoolean()) {
+                listener.onFailure(new OpenSearchException("simulated"));
+            } else {
+                listener.onResponse(clusterService.state());
+            }
             assertEquals("reroute after balanced shards allocator timed out", reason);
             assertEquals(Priority.HIGH, priority);
             rerouteScheduled.compareAndSet(false, true);
diff --git a/server/src/test/java/org/opensearch/gateway/GatewayAllocatorTests.java b/server/src/test/java/org/opensearch/gateway/GatewayAllocatorTests.java
index 61b53d688d330..d9120e1a6b37f 100644
--- a/server/src/test/java/org/opensearch/gateway/GatewayAllocatorTests.java
+++ b/server/src/test/java/org/opensearch/gateway/GatewayAllocatorTests.java
@@ -10,6 +10,7 @@
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.opensearch.OpenSearchException;
 import org.opensearch.Version;
 import org.opensearch.action.support.nodes.BaseNodeResponse;
 import org.opensearch.cluster.ClusterInfo;
@@ -437,7 +438,11 @@ public void testCollectTimedOutShardsAndScheduleReroute() throws InterruptedExce
         ClusterService clusterService = ClusterServiceUtils.createClusterService(clusterState, threadPool);
         final CountDownLatch rerouteLatch = new CountDownLatch(2);
         final RerouteService rerouteService = (reason, priority, listener) -> {
-            listener.onResponse(clusterService.state());
+            if (randomBoolean()) {
+                listener.onFailure(new OpenSearchException("simulated"));
+            } else {
+                listener.onResponse(clusterService.state());
+            }
             assertThat(rerouteLatch.getCount(), greaterThanOrEqualTo(0L));
             assertEquals("reroute after existing shards allocator timed out", reason);
             assertEquals(Priority.HIGH, priority);
@@ -454,7 +459,7 @@ public void testCollectTimedOutShardsAndScheduleReroute() throws InterruptedExce
         executor = testShardsBatchGatewayAllocator.allocateAllUnassignedShards(testAllocation, false);
         executor.run();
         assertEquals(timedOutShardsLatch.getCount(), 0);
-        assertEquals(0, rerouteLatch.getCount());
+        assertEquals(0, rerouteLatch.getCount()); // even with failure it doesn't leak any listeners
         final boolean terminated = terminate(threadPool);
         assert terminated;
         clusterService.close();