diff --git a/ambari-server/src/main/java/org/apache/ambari/server/checks/PreviousUpgradeCompleted.java b/ambari-server/src/main/java/org/apache/ambari/server/checks/PreviousUpgradeCompleted.java
index 4af0896..3a4467f 100644
--- a/ambari-server/src/main/java/org/apache/ambari/server/checks/PreviousUpgradeCompleted.java
+++ b/ambari-server/src/main/java/org/apache/ambari/server/checks/PreviousUpgradeCompleted.java
@@ -102,7 +102,7 @@
         for (UpgradeEntity downgrade : upgrades) {
           // Surprisingly, a Downgrade's from and to version are identical.
           if (downgrade.getClusterId() == cluster.getClusterId() && downgrade.getDirection() == Direction.DOWNGRADE &&
-              downgrade.getFromVersion().equals(mostRecentUpgrade.getToVersion())) {
+              downgrade.getFromVersion().equals(mostRecentUpgrade.getFromVersion())) {
             correspondingDowngrade = downgrade;
             break;
           }
diff --git a/ambari-server/src/test/java/org/apache/ambari/server/checks/PreviousUpgradeCompletedTest.java b/ambari-server/src/test/java/org/apache/ambari/server/checks/PreviousUpgradeCompletedTest.java
new file mode 100644
index 0000000..2005e36
--- /dev/null
+++ b/ambari-server/src/test/java/org/apache/ambari/server/checks/PreviousUpgradeCompletedTest.java
@@ -0,0 +1,220 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.ambari.server.checks;
+
+import com.google.inject.Provider;
+import org.apache.ambari.server.actionmanager.HostRoleStatus;
+import org.apache.ambari.server.api.services.AmbariMetaInfo;
+import org.apache.ambari.server.controller.PrereqCheckRequest;
+import org.apache.ambari.server.orm.dao.ClusterVersionDAO;
+import org.apache.ambari.server.orm.dao.HostRoleCommandDAO;
+import org.apache.ambari.server.orm.dao.RequestDAO;
+import org.apache.ambari.server.orm.dao.UpgradeDAO;
+import org.apache.ambari.server.orm.entities.HostRoleCommandEntity;
+import org.apache.ambari.server.orm.entities.RepositoryVersionEntity;
+import org.apache.ambari.server.orm.entities.RequestEntity;
+import org.apache.ambari.server.orm.entities.StackEntity;
+import org.apache.ambari.server.orm.entities.UpgradeEntity;
+import org.apache.ambari.server.state.Cluster;
+import org.apache.ambari.server.state.Clusters;
+import org.apache.ambari.server.state.StackId;
+import org.apache.ambari.server.state.stack.PrereqCheckStatus;
+import org.apache.ambari.server.state.stack.PrerequisiteCheck;
+import org.apache.ambari.server.state.stack.upgrade.Direction;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mockito;
+
+import java.util.ArrayList;
+import java.util.List;
+
+
+/**
+ * Unit tests for PreviousUpgradeCompleted
+ *
+ */
+public class PreviousUpgradeCompletedTest {
+
+  private final Clusters clusters = Mockito.mock(Clusters.class);
+  private final ClusterVersionDAO clusterVersionDAO = Mockito.mock(ClusterVersionDAO.class);
+  private AmbariMetaInfo ambariMetaInfo = Mockito.mock(AmbariMetaInfo.class);
+  private final RequestDAO requestDAO = Mockito.mock(RequestDAO.class);
+  private HostRoleCommandDAO hrcDAO = Mockito.mock(HostRoleCommandDAO.class);
+  private UpgradeDAO upgradeDAO = Mockito.mock(UpgradeDAO.class);
+
+  private StackId sourceStackId = new StackId("HDP", "2.2");
+  private StackId targetStackId = new StackId("HDP", "2.2");
+  private String sourceRepositoryVersion = "2.2.6.0-1234";
+  private String destRepositoryVersion = "2.2.8.0-5678";
+  private String clusterName = "cluster";
+
+  private PreviousUpgradeCompleted puc;
+  /**
+   *
+   */
+  @Before
+  public void setup() {
+    puc = new PreviousUpgradeCompleted();
+    puc.clustersProvider = new Provider<Clusters>() {
+      @Override
+      public Clusters get() {
+        return clusters;
+      }
+    };
+
+    puc.ambariMetaInfo = new Provider<AmbariMetaInfo>() {
+      @Override
+      public AmbariMetaInfo get() {
+        return ambariMetaInfo;
+      }
+    };
+
+    puc.clusterVersionDAOProvider = new Provider<ClusterVersionDAO>() {
+      @Override
+      public ClusterVersionDAO get() {
+        return clusterVersionDAO;
+      }
+    };
+
+    puc.requestDaoProvider = new Provider<RequestDAO>() {
+      @Override
+      public RequestDAO get() {
+        return requestDAO;
+      }
+    };
+
+    puc.hostRoleCommandDaoProvider = new Provider<HostRoleCommandDAO>() {
+      @Override
+      public HostRoleCommandDAO get() {
+        return hrcDAO;
+      }
+    };
+
+    puc.upgradeDaoProvider = new Provider<UpgradeDAO>() {
+      @Override
+      public UpgradeDAO get() {
+        return upgradeDAO;
+      }
+    };
+  }
+
+  @Test
+  public void testPerform() throws Exception {
+    StackId stackId = new StackId("HDP", "2.2");
+
+    StackEntity stack = new StackEntity();
+    stack.setStackName(stackId.getStackName());
+    stack.setStackVersion(stackId.getStackVersion());
+    RepositoryVersionEntity rve = new RepositoryVersionEntity(stack, sourceRepositoryVersion, sourceRepositoryVersion, "rhel6");
+    final Cluster cluster = Mockito.mock(Cluster.class);
+    Mockito.when(cluster.getClusterName()).thenReturn(clusterName);
+    final long clusterId = 1L;
+    Mockito.when(cluster.getClusterId()).thenReturn(clusterId);
+
+    PrereqCheckRequest checkRequest = new PrereqCheckRequest(clusterName);
+    checkRequest.setRepositoryVersion(sourceRepositoryVersion);
+    checkRequest.setSourceStackId(sourceStackId);
+    checkRequest.setTargetStackId(targetStackId);
+
+    List<UpgradeEntity> upgrades = new ArrayList<>();
+    Mockito.when(upgradeDAO.findAll()).thenReturn(upgrades);
+
+    Mockito.when(clusters.getCluster(clusterName)).thenReturn(cluster);
+
+    
+    // Case 1. No previous upgrades
+    PrerequisiteCheck check = new PrerequisiteCheck(null, null);
+    puc.perform(check, checkRequest);
+    Assert.assertEquals(PrereqCheckStatus.PASS, check.getStatus());
+
+
+    // Case 2. Initialize with only one completed upgrade
+    final long upgradeRequestId = 1L;
+    RequestEntity upgradeRequest = Mockito.mock(RequestEntity.class);
+    Mockito.when(upgradeRequest.getRequestId()).thenReturn(upgradeRequestId);
+    Mockito.when(upgradeRequest.getStartTime()).thenReturn(System.currentTimeMillis() - 1000);
+    Mockito.when(requestDAO.findByPK(upgradeRequestId)).thenReturn(upgradeRequest);
+
+    UpgradeEntity upgrade = Mockito.mock(UpgradeEntity.class);
+    Mockito.when(upgrade.getClusterId()).thenReturn(clusterId);
+    Mockito.when(upgrade.getRequestId()).thenReturn(upgradeRequestId);
+    Mockito.when(upgrade.getDirection()).thenReturn(Direction.UPGRADE);
+    Mockito.when(upgrade.getFromVersion()).thenReturn(sourceRepositoryVersion);
+    Mockito.when(upgrade.getToVersion()).thenReturn(destRepositoryVersion);
+
+    upgrades.add(upgrade);
+    Mockito.when(upgradeDAO.findAll()).thenReturn(upgrades);
+
+    check = new PrerequisiteCheck(null, null);
+    puc.perform(check, checkRequest);
+    Assert.assertEquals(PrereqCheckStatus.PASS, check.getStatus());
+
+
+    // Case 3. Initialize with a successful downgrade.
+    final long downgradeRequestId = 2L;
+    RequestEntity downgradeRequest = Mockito.mock(RequestEntity.class);
+    Mockito.when(downgradeRequest.getRequestId()).thenReturn(downgradeRequestId);
+    Mockito.when(downgradeRequest.getStartTime()).thenReturn(System.currentTimeMillis() - 500);
+    Mockito.when(requestDAO.findByPK(downgradeRequestId)).thenReturn(downgradeRequest);
+
+    UpgradeEntity downgrade = Mockito.mock(UpgradeEntity.class);
+    Mockito.when(downgrade.getClusterId()).thenReturn(clusterId);
+    Mockito.when(downgrade.getRequestId()).thenReturn(downgradeRequestId);
+    Mockito.when(downgrade.getDirection()).thenReturn(Direction.DOWNGRADE);
+    Mockito.when(downgrade.getFromVersion()).thenReturn(sourceRepositoryVersion);
+    Mockito.when(downgrade.getToVersion()).thenReturn(sourceRepositoryVersion);
+
+    upgrades.clear();
+    upgrades.add(upgrade);
+    upgrades.add(downgrade);
+    Mockito.when(upgradeDAO.findAll()).thenReturn(upgrades);
+
+    check = new PrerequisiteCheck(null, null);
+    puc.perform(check, checkRequest);
+    Assert.assertEquals(PrereqCheckStatus.PASS, check.getStatus());
+
+
+    // Case 4. The upgrade has no downgrade, and it has a COMPLETED "Save Cluster State" step, so it should pass.
+    HostRoleCommandEntity finalizeCommand = Mockito.mock(HostRoleCommandEntity.class);
+    Mockito.when(finalizeCommand.getStatus()).thenReturn(HostRoleStatus.COMPLETED);
+    Mockito.when(finalizeCommand.getTaskId()).thenReturn(1000L);
+    List<HostRoleCommandEntity> commands = new ArrayList<>();
+    commands.add(finalizeCommand);
+    Mockito.when(hrcDAO.findSortedCommandsByRequestIdAndCustomCommandName(upgradeRequestId, PreviousUpgradeCompleted.FINALIZE_ACTION_CLASS_NAME)).thenReturn(commands);
+
+    upgrades.clear();
+    upgrades.add(upgrade);
+    Mockito.when(upgradeDAO.findAll()).thenReturn(upgrades);
+
+    check = new PrerequisiteCheck(null, null);
+    puc.perform(check, checkRequest);
+    Assert.assertEquals(PrereqCheckStatus.PASS, check.getStatus());
+
+
+    // Case 5. The upgrade has no downgrade, and it has an ABORTED "Save Cluster State" step, so it should fail.
+    Mockito.when(finalizeCommand.getStatus()).thenReturn(HostRoleStatus.ABORTED);
+    upgrades.clear();
+    upgrades.add(upgrade);
+    Mockito.when(upgradeDAO.findAll()).thenReturn(upgrades);
+
+    check = new PrerequisiteCheck(null, null);
+    puc.perform(check, checkRequest);
+    Assert.assertEquals(PrereqCheckStatus.FAIL, check.getStatus());
+  }
+}