diff --git a/helix-rest/src/main/java/org/apache/helix/rest/server/resources/helix/PerInstanceAccessor.java b/helix-rest/src/main/java/org/apache/helix/rest/server/resources/helix/PerInstanceAccessor.java
index b920f66ce8..b1b4f82642 100644
--- a/helix-rest/src/main/java/org/apache/helix/rest/server/resources/helix/PerInstanceAccessor.java
+++ b/helix-rest/src/main/java/org/apache/helix/rest/server/resources/helix/PerInstanceAccessor.java
@@ -436,15 +436,11 @@ public Response updateInstance(@PathParam("clusterId") String clusterId,
           admin.setInstanceOperation(clusterId, instanceName, state);
           break;
         case canCompleteSwap:
-          if (!admin.canCompleteSwap(clusterId, instanceName)) {
-            return badRequest("Swap is not ready to be completed!");
-          }
-          break;
+          return OK(OBJECT_MAPPER.writeValueAsString(
+              Map.of("successful", admin.canCompleteSwap(clusterId, instanceName))));
         case completeSwapIfPossible:
-          if (!admin.completeSwapIfPossible(clusterId, instanceName)) {
-            return badRequest("Swap is not ready to be completed!");
-          }
-          break;
+          return OK(OBJECT_MAPPER.writeValueAsString(
+              Map.of("successful", admin.completeSwapIfPossible(clusterId, instanceName))));
         case addInstanceTag:
           if (!validInstance(node, instanceName)) {
             return badRequest("Instance names are not match!");
diff --git a/helix-rest/src/test/java/org/apache/helix/rest/server/TestPerInstanceAccessor.java b/helix-rest/src/test/java/org/apache/helix/rest/server/TestPerInstanceAccessor.java
index 273019bd3f..a8675202a3 100644
--- a/helix-rest/src/test/java/org/apache/helix/rest/server/TestPerInstanceAccessor.java
+++ b/helix-rest/src/test/java/org/apache/helix/rest/server/TestPerInstanceAccessor.java
@@ -501,6 +501,26 @@ public void updateInstance() throws IOException {
     instanceConfig = _configAccessor.getInstanceConfig(CLUSTER_NAME, INSTANCE_NAME);
     Assert.assertEquals(
         instanceConfig.getInstanceOperation(), "");
+
+    // test canCompleteSwap
+    Response canCompleteSwapResponse =
+        new JerseyUriRequestBuilder("clusters/{}/instances/{}?command=canCompleteSwap").format(
+            CLUSTER_NAME, INSTANCE_NAME).post(this, entity);
+    Assert.assertEquals(canCompleteSwapResponse.getStatus(), Response.Status.OK.getStatusCode());
+    Map<String, Object> responseMap =
+        OBJECT_MAPPER.readValue(canCompleteSwapResponse.readEntity(String.class), Map.class);
+    Assert.assertFalse((boolean) responseMap.get("successful"));
+
+    // test completeSwapIfPossible
+    Response completeSwapIfPossibleResponse = new JerseyUriRequestBuilder(
+        "clusters/{}/instances/{}?command=completeSwapIfPossible").format(CLUSTER_NAME,
+        INSTANCE_NAME).post(this, entity);
+    Assert.assertEquals(completeSwapIfPossibleResponse.getStatus(),
+        Response.Status.OK.getStatusCode());
+    responseMap =
+        OBJECT_MAPPER.readValue(completeSwapIfPossibleResponse.readEntity(String.class), Map.class);
+    Assert.assertFalse((boolean) responseMap.get("successful"));
+
     System.out.println("End test :" + TestHelper.getTestMethodName());
   }