diff --git a/CHANGELOG.md b/CHANGELOG.md
index 798802f11ebad..ea6ba7e6a73fc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -43,6 +43,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fix search_as_you_type not supporting multi-fields ([#15988](https://github.com/opensearch-project/OpenSearch/pull/15988))
 - Avoid infinite loop when `flat_object` field contains invalid token ([#15985](https://github.com/opensearch-project/OpenSearch/pull/15985))
 - Fix infinite loop in nested agg ([#15931](https://github.com/opensearch-project/OpenSearch/pull/15931))
+- Fix missing fields in task index mapping to ensure proper task result storage ([#16201](https://github.com/opensearch-project/OpenSearch/pull/16201))
 
 ### Security
 
diff --git a/server/src/internalClusterTest/java/org/opensearch/action/admin/cluster/node/tasks/TasksIT.java b/server/src/internalClusterTest/java/org/opensearch/action/admin/cluster/node/tasks/TasksIT.java
index c7d75108883dd..2f68505b6962d 100644
--- a/server/src/internalClusterTest/java/org/opensearch/action/admin/cluster/node/tasks/TasksIT.java
+++ b/server/src/internalClusterTest/java/org/opensearch/action/admin/cluster/node/tasks/TasksIT.java
@@ -60,6 +60,9 @@
 import org.opensearch.common.settings.Settings;
 import org.opensearch.core.action.ActionListener;
 import org.opensearch.core.tasks.TaskId;
+import org.opensearch.core.tasks.resourcetracker.TaskResourceStats;
+import org.opensearch.core.tasks.resourcetracker.TaskResourceUsage;
+import org.opensearch.core.tasks.resourcetracker.TaskThreadUsage;
 import org.opensearch.core.xcontent.MediaTypeRegistry;
 import org.opensearch.index.query.QueryBuilders;
 import org.opensearch.search.builder.SearchSourceBuilder;
@@ -921,4 +924,58 @@ public void onFailure(Exception e) {
         assertNotNull(response.getTask().getError());
         assertNull(response.getTask().getResponse());
     }
+
+    public void testStoreResultWithAllFields() throws Exception {
+        // given
+        CyclicBarrier b = new CyclicBarrier(2);
+        TaskResultsService resultsService = internalCluster().getInstance(TaskResultsService.class);
+
+        // when
+        resultsService.storeResult(
+            new TaskResult(
+                new TaskInfo(
+                    new TaskId("fake", 1),
+                    "test",
+                    "test",
+                    "",
+                    null,
+                    0,
+                    0,
+                    false,
+                    false,
+                    TaskId.EMPTY_TASK_ID,
+                    Collections.emptyMap(),
+                    new TaskResourceStats(new HashMap<>() {
+                        {
+                            put("dummy-type1", new TaskResourceUsage(100, 100));
+                        }
+                    }, new TaskThreadUsage(10, 10)),
+                    0L
+                ),
+                new RuntimeException("test")
+            ),
+            new ActionListener<Void>() {
+                @Override
+                public void onResponse(Void response) {
+                    try {
+                        b.await();
+                    } catch (InterruptedException | BrokenBarrierException e) {
+                        onFailure(e);
+                    }
+                }
+
+                @Override
+                public void onFailure(Exception e) {
+                    throw new RuntimeException(e);
+                }
+            }
+        );
+        b.await();
+
+        // then
+        GetTaskResponse response = expectFinishedTask(new TaskId("fake:1"));
+        assertEquals("test", response.getTask().getTask().getAction());
+        assertNotNull(response.getTask().getError());
+        assertNull(response.getTask().getResponse());
+    }
 }
diff --git a/server/src/main/java/org/opensearch/tasks/TaskResultsService.java b/server/src/main/java/org/opensearch/tasks/TaskResultsService.java
index d1ee04bd5cb25..3d11bf77ae32a 100644
--- a/server/src/main/java/org/opensearch/tasks/TaskResultsService.java
+++ b/server/src/main/java/org/opensearch/tasks/TaskResultsService.java
@@ -85,7 +85,7 @@ public class TaskResultsService {
 
     public static final String TASK_RESULT_MAPPING_VERSION_META_FIELD = "version";
 
-    public static final int TASK_RESULT_MAPPING_VERSION = 4; // must match version in task-index-mapping.json
+    public static final int TASK_RESULT_MAPPING_VERSION = 5; // must match version in task-index-mapping.json
 
     /**
      * The backoff policy to use when saving a task result fails. The total wait
diff --git a/server/src/main/resources/org/opensearch/tasks/task-index-mapping.json b/server/src/main/resources/org/opensearch/tasks/task-index-mapping.json
index 58b6b2d3bc873..21d418c472898 100644
--- a/server/src/main/resources/org/opensearch/tasks/task-index-mapping.json
+++ b/server/src/main/resources/org/opensearch/tasks/task-index-mapping.json
@@ -1,7 +1,7 @@
 {
   "_doc" : {
     "_meta": {
-      "version": 4
+      "version": 5
     },
     "dynamic" : "strict",
     "properties" : {
@@ -34,6 +34,9 @@
           "start_time_in_millis": {
             "type": "long"
           },
+          "cancellation_time_millis": {
+            "type": "long"
+          },
           "type": {
             "type": "keyword"
           },
@@ -47,6 +50,10 @@
           "headers": {
             "type" : "object",
             "enabled" : false
+          },
+          "resource_stats": {
+            "type" : "object",
+            "enabled" : false
           }
         }
       },