diff --git a/python/packages/devui/agent_framework_devui/_mapper.py b/python/packages/devui/agent_framework_devui/_mapper.py
index f68fea9d01..5adff1cd2f 100644
--- a/python/packages/devui/agent_framework_devui/_mapper.py
+++ b/python/packages/devui/agent_framework_devui/_mapper.py
@@ -840,7 +840,9 @@ async def _convert_workflow_event(self, event: Any, context: dict[str, Any]) ->
 
             if event_class == "WorkflowFailedEvent":
                 workflow_id = context.get("workflow_id", str(uuid4()))
-                error_info = getattr(event, "error", None)
+                # WorkflowFailedEvent uses 'details' field (WorkflowErrorDetails), not 'error'
+                # This matches ExecutorFailedEvent which also uses 'details'
+                details = getattr(event, "details", None)
 
                 # Import Response and ResponseError types
                 from openai.types.responses import Response, ResponseError
@@ -849,8 +851,14 @@ async def _convert_workflow_event(self, event: Any, context: dict[str, Any]) ->
                 request_obj = context.get("request")
                 model_name = request_obj.model if request_obj and request_obj.model else "devui"
 
-                # Create error object
-                error_message = str(error_info) if error_info else "Unknown error"
+                # Extract error message from WorkflowErrorDetails
+                if details:
+                    error_message = getattr(details, "message", None) or str(details)
+                    extra = getattr(details, "extra", None)
+                    if extra:
+                        error_message = f"{error_message} (extra: {extra})"
+                else:
+                    error_message = "Unknown error"
 
                 # Create ResponseError object (code must be one of the allowed values)
                 response_error = ResponseError(
@@ -945,7 +953,13 @@ async def _convert_workflow_event(self, event: Any, context: dict[str, Any]) ->
                 item_id = context.get(f"exec_item_{executor_id}", f"exec_{executor_id}_unknown")
                 # ExecutorFailedEvent uses 'details' field (WorkflowErrorDetails), not 'error'
                 details = getattr(event, "details", None)
-                err_msg: str | None = str(getattr(details, "message", details)) if details else None
+                if details:
+                    err_msg = getattr(details, "message", None) or str(details)
+                    extra = getattr(details, "extra", None)
+                    if extra:
+                        err_msg = f"{err_msg} (extra: {extra})"
+                else:
+                    err_msg = None
 
                 # Create ExecutorActionItem with failed status
                 executor_item = ExecutorActionItem(
diff --git a/python/packages/devui/tests/test_mapper.py b/python/packages/devui/tests/test_mapper.py
index eaaec77313..6557dea527 100644
--- a/python/packages/devui/tests/test_mapper.py
+++ b/python/packages/devui/tests/test_mapper.py
@@ -596,6 +596,31 @@ async def test_workflow_failed_event(mapper: MessageMapper, test_request: AgentF
     response = failed_events[0].response
     assert response.status == "failed"
     assert response.error is not None
+    # Verify error message is correctly extracted from details.message (not "Unknown error")
+    assert "Workflow failed due to test error" in response.error.message
+    assert "Unknown error" not in response.error.message
+
+
+async def test_workflow_failed_event_with_extra(mapper: MessageMapper, test_request: AgentFrameworkRequest) -> None:
+    """Test WorkflowFailedEvent includes extra context when available."""
+    from agent_framework._workflows._events import WorkflowErrorDetails, WorkflowFailedEvent
+
+    details = WorkflowErrorDetails(
+        error_type="ValidationError",
+        message="Input validation failed",
+        executor_id="validation_executor",
+        extra={"field": "email", "reason": "invalid format"},
+    )
+    event = WorkflowFailedEvent(details=details)
+    events = await mapper.convert_event(event, test_request)
+
+    assert len(events) == 1
+    assert events[0].type == "response.failed"
+    response = events[0].response
+    # Verify both the message and extra context are included
+    assert "Input validation failed" in response.error.message
+    assert "extra:" in response.error.message
+    assert "email" in response.error.message
 
 
 async def test_workflow_failed_event_with_traceback(mapper: MessageMapper, test_request: AgentFrameworkRequest) -> None: