[9.2] [Cases][Connector] Improve IBM error message (#244012) (#244084)

# Backport

This will backport the following commits from `main` to `9.2`:
- [[Cases][Connector] Improve IBM error message
(#244012)](#244012)

<!--- Backport version: 9.6.6 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sorenlouv/backport)

<!--BACKPORT [{"author":{"name":"Jan
Monschke","email":"[email protected]"},"sourceCommit":{"committedDate":"2025-11-25T06:34:17Z","message":"[Cases][Connector]
Improve IBM error message (#244012)\n\n## Summary\n\nAddresses:
https://github.com/elastic/kibana/issues/243994\n\nImproves the error
message when the connector fails:\n\nBefore:\n<img width=\"1083\"
height=\"407\" alt=\"Screenshot 2025-11-24 at 15 16
55\"\nsrc=\"https://github.com/user-attachments/assets/a8efb8c7-96ce-43a1-a349-27683f31bb97\"\n/>\n\n\nAfter:\n<img
width=\"1119\" height=\"580\" alt=\"Screenshot 2025-11-24 at 15 57
38\"\nsrc=\"https://github.com/user-attachments/assets/e2b282a4-5255-4e72-9644-455416f8efaf\"\n/>","sha":"82bd200a76f5b43cb75e04bb932d218035aba25c","branchLabelMapping":{"^v9.3.0$":"main","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:fix","backport:version","Team:Cases","v9.2.0","v9.3.0"],"title":"[Cases][Connector]
Improve IBM error
message","number":244012,"url":"https://github.com/elastic/kibana/pull/244012","mergeCommit":{"message":"[Cases][Connector]
Improve IBM error message (#244012)\n\n## Summary\n\nAddresses:
https://github.com/elastic/kibana/issues/243994\n\nImproves the error
message when the connector fails:\n\nBefore:\n<img width=\"1083\"
height=\"407\" alt=\"Screenshot 2025-11-24 at 15 16
55\"\nsrc=\"https://github.com/user-attachments/assets/a8efb8c7-96ce-43a1-a349-27683f31bb97\"\n/>\n\n\nAfter:\n<img
width=\"1119\" height=\"580\" alt=\"Screenshot 2025-11-24 at 15 57
38\"\nsrc=\"https://github.com/user-attachments/assets/e2b282a4-5255-4e72-9644-455416f8efaf\"\n/>","sha":"82bd200a76f5b43cb75e04bb932d218035aba25c"}},"sourceBranch":"main","suggestedTargetBranches":["9.2"],"targetPullRequestStates":[{"branch":"9.2","label":"v9.2.0","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"main","label":"v9.3.0","branchLabelMappingKey":"^v9.3.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/244012","number":244012,"mergeCommit":{"message":"[Cases][Connector]
Improve IBM error message (#244012)\n\n## Summary\n\nAddresses:
https://github.com/elastic/kibana/issues/243994\n\nImproves the error
message when the connector fails:\n\nBefore:\n<img width=\"1083\"
height=\"407\" alt=\"Screenshot 2025-11-24 at 15 16
55\"\nsrc=\"https://github.com/user-attachments/assets/a8efb8c7-96ce-43a1-a349-27683f31bb97\"\n/>\n\n\nAfter:\n<img
width=\"1119\" height=\"580\" alt=\"Screenshot 2025-11-24 at 15 57
38\"\nsrc=\"https://github.com/user-attachments/assets/e2b282a4-5255-4e72-9644-455416f8efaf\"\n/>","sha":"82bd200a76f5b43cb75e04bb932d218035aba25c"}}]}]
BACKPORT-->

Co-authored-by: Jan Monschke <[email protected]>

Author: kibanamachine

x-pack/platform/plugins/shared/stack_connectors/server/connector_types/resilient/resilient.test.ts

@@ -5,6 +5,7 @@
  * 2.0.
  */
 
+import { AxiosError, type AxiosResponse } from 'axios';
 import { request, createAxiosResponse } from '@kbn/actions-plugin/server/lib/axios_utils';
 import { loggingSystemMock } from '@kbn/core/server/mocks';
 import { resilientFields, incidentTypes, severity } from './mocks';
@@ -173,6 +174,32 @@ describe('IBM Resilient connector', () => {
         'Unable to get incident with id 1. Error: An error has occurred'
       );
     });
+
+    it('should read message from response body if available', async () => {
+      requestMock.mockImplementation(() => {
+        const err = new AxiosError('An error has occurred');
+        err.response = {
+          status: 400,
+          data: { message: 'A test error message' },
+        } as AxiosResponse;
+        throw err;
+      });
+
+      await expect(
+        connector.createIncident(
+          {
+            name: 'title',
+            description: 'desc',
+            incidentTypes: [1001],
+            severityCode: 6,
+            additionalFields: null,
+          },
+          connectorUsageCollector
+        )
+      ).rejects.toThrow(
+        '[Action][IBM Resilient]: Unable to create incident. Error: Status code: 400. Message: API Error: A test error message.'
+      );
+    });
   });
 
   describe('createIncident', () => {

x-pack/platform/plugins/shared/stack_connectors/server/connector_types/resilient/resilient.ts

@@ -6,7 +6,7 @@
  */
 
 import type { AxiosError } from 'axios';
-import { omitBy, isNil } from 'lodash/fp';
+import { omitBy, isNil, isObject } from 'lodash/fp';
 import type { ServiceParams } from '@kbn/actions-plugin/server';
 import { CaseConnector, getBasicAuthHeader } from '@kbn/actions-plugin/server';
 import type { Type } from '@kbn/config-schema';
@@ -76,6 +76,9 @@ export class ResilientConnector extends CaseConnector<
     if (error.response.status === 401) {
       return i18n.UNAUTHORIZED_API_ERROR;
     }
+    if (isObject(error.response?.data) && 'message' in error.response.data) {
+      return `API Error: ${error.response.data.message}`;
+    }
     return `API Error: ${error.response?.statusText}`;
   }