diff --git a/public/pages/CreateDetector/containers/CreateDetector.tsx b/public/pages/CreateDetector/containers/CreateDetector.tsx
index b3f833b71..499c2a6e4 100644
--- a/public/pages/CreateDetector/containers/CreateDetector.tsx
+++ b/public/pages/CreateDetector/containers/CreateDetector.tsx
@@ -32,6 +32,7 @@ import { NotificationsStart } from 'opensearch-dashboards/public';
 import { getPlugins } from '../../../utils/helpers';
 import { Detector } from '../../../../types';
 import { DataStore } from '../../../store/DataStore';
+import { errorNotificationToast } from '../../../utils/helpers';
 
 interface CreateDetectorProps extends RouteComponentProps {
   isEdit: boolean;
@@ -109,7 +110,7 @@ export default class CreateDetector extends Component<CreateDetectorProps, Creat
     this.setState({ fieldMappings });
   };
 
-  onCreateClick = () => {
+  onCreateClick = async () => {
     const { creatingDetector, detector, fieldMappings } = this.state;
     if (creatingDetector) {
       return;
@@ -123,6 +124,19 @@ export default class CreateDetector extends Component<CreateDetectorProps, Creat
       fieldMappings
     );
 
+    const fieldMappingRes = await fieldsMappingPromise;
+
+    if (!fieldMappingRes.ok) {
+      errorNotificationToast(
+        this.props.notifications,
+        'create',
+        'detector',
+        'Invalid field mappings.'
+      );
+      this.setState({ creatingDetector: false });
+      return;
+    }
+
     const createDetectorPromise = this.props.services.detectorsService.createDetector(detector);
 
     // set detector pending state, this will be used in detector details page
diff --git a/public/services/FieldMappingService.ts b/public/services/FieldMappingService.ts
index 18431fed1..24c455a52 100644
--- a/public/services/FieldMappingService.ts
+++ b/public/services/FieldMappingService.ts
@@ -43,6 +43,10 @@ export default class FieldMappingService {
       properties: {},
     };
     fieldMappings.forEach((mapping) => {
+      if (mapping.ruleFieldName === mapping.indexFieldName) {
+        return;
+      }
+
       alias_mappings.properties[mapping.ruleFieldName] = {
         type: 'alias',
         path: mapping.indexFieldName,