diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/indexlifecycle/ShrinkStep.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/indexlifecycle/ShrinkStep.java
index 6f14c35c48a..16fbf7dbc31 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/indexlifecycle/ShrinkStep.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/indexlifecycle/ShrinkStep.java
@@ -56,6 +56,8 @@ public class ShrinkStep extends AsyncActionStep {
             .put(LifecycleSettings.LIFECYCLE_PHASE, phase)
             .put(LifecycleSettings.LIFECYCLE_ACTION, action)
             .put(LifecycleSettings.LIFECYCLE_STEP, ShrunkenIndexCheckStep.NAME) // skip source-index steps
+            .put(IndexMetaData.INDEX_ROUTING_REQUIRE_GROUP_SETTING.getKey() + "_name", (String) null) // need to remove the single shard 
+                                                                                             // allocation so replicas can be allocated
             .build();
         String shrunkenIndexName = shrunkIndexPrefix + indexMetaData.getIndex().getName();
         ResizeRequest resizeRequest = new ResizeRequest(shrunkenIndexName, indexMetaData.getIndex().getName());
diff --git a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/ShrinkStepTests.java b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/ShrinkStepTests.java
index 51ef2ea8d9e..c66a29cb8b3 100644
--- a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/ShrinkStepTests.java
+++ b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/ShrinkStepTests.java
@@ -119,6 +119,7 @@ public class ShrinkStepTests extends AbstractStepTestCase<ShrinkStep> {
                     .put(LifecycleSettings.LIFECYCLE_PHASE, step.getKey().getPhase())
                     .put(LifecycleSettings.LIFECYCLE_ACTION, step.getKey().getAction())
                     .put(LifecycleSettings.LIFECYCLE_STEP, ShrunkenIndexCheckStep.NAME)
+                    .put(IndexMetaData.INDEX_ROUTING_REQUIRE_GROUP_SETTING.getKey() + "_name", (String) null)
                     .build()));
                 assertThat(request.getTargetIndexRequest().settings()
                         .getAsInt(IndexMetaData.SETTING_NUMBER_OF_SHARDS, -1), equalTo(step.getNumberOfShards()));
diff --git a/x-pack/plugin/ilm/src/main/java/org/elasticsearch/xpack/indexlifecycle/action/RestExplainLifecycleAction.java b/x-pack/plugin/ilm/src/main/java/org/elasticsearch/xpack/indexlifecycle/action/RestExplainLifecycleAction.java
index 3b3981fc38b..044a9f16d29 100644
--- a/x-pack/plugin/ilm/src/main/java/org/elasticsearch/xpack/indexlifecycle/action/RestExplainLifecycleAction.java
+++ b/x-pack/plugin/ilm/src/main/java/org/elasticsearch/xpack/indexlifecycle/action/RestExplainLifecycleAction.java
@@ -37,7 +37,10 @@ public class RestExplainLifecycleAction extends BaseRestHandler {
         ExplainLifecycleRequest explainLifecycleRequest = new ExplainLifecycleRequest();
         explainLifecycleRequest.indices(indexes);
         explainLifecycleRequest.indicesOptions(IndicesOptions.fromRequest(restRequest, IndicesOptions.strictExpandOpen()));
-        explainLifecycleRequest.masterNodeTimeout(restRequest.param("master_timeout"));
+        String masterNodeTimeout = restRequest.param("master_timeout");
+        if (masterNodeTimeout != null) {
+            explainLifecycleRequest.masterNodeTimeout(masterNodeTimeout);
+        }
 
         return channel -> client.execute(ExplainLifecycleAction.INSTANCE, explainLifecycleRequest, new RestToXContentListener<>(channel));
     }