diff --git a/src/a2a/server/request_handlers/default_request_handler.py b/src/a2a/server/request_handlers/default_request_handler.py
index 2c71a6e51..ee406d6bc 100644
--- a/src/a2a/server/request_handlers/default_request_handler.py
+++ b/src/a2a/server/request_handlers/default_request_handler.py
@@ -344,15 +344,6 @@ async def push_notification_callback() -> None:
                 blocking=blocking,
                 event_callback=push_notification_callback,
             )
-            if not result:
-                raise ServerError(error=InternalError())  # noqa: TRY301
-
-            if isinstance(result, Task):
-                self._validate_task_id_match(task_id, result.id)
-
-            await self._send_push_notification_if_needed(
-                task_id, result_aggregator
-            )
 
         except Exception:
             logger.exception('Agent execution failed')
@@ -367,6 +358,14 @@ async def push_notification_callback() -> None:
             else:
                 await self._cleanup_producer(producer_task, task_id)
 
+        if not result:
+            raise ServerError(error=InternalError())
+
+        if isinstance(result, Task):
+            self._validate_task_id_match(task_id, result.id)
+
+        await self._send_push_notification_if_needed(task_id, result_aggregator)
+
         return result
 
     async def on_message_send_stream(
diff --git a/src/a2a/server/request_handlers/jsonrpc_handler.py b/src/a2a/server/request_handlers/jsonrpc_handler.py
index 2cee937f4..567c61484 100644
--- a/src/a2a/server/request_handlers/jsonrpc_handler.py
+++ b/src/a2a/server/request_handlers/jsonrpc_handler.py
@@ -183,15 +183,6 @@ async def on_cancel_task(
             task = await self.request_handler.on_cancel_task(
                 request.params, context
             )
-            if task:
-                return prepare_response_object(
-                    request.id,
-                    task,
-                    (Task,),
-                    CancelTaskSuccessResponse,
-                    CancelTaskResponse,
-                )
-            raise ServerError(error=TaskNotFoundError())  # noqa: TRY301
         except ServerError as e:
             return CancelTaskResponse(
                 root=JSONRPCErrorResponse(
@@ -199,6 +190,19 @@ async def on_cancel_task(
                 )
             )
 
+        if task:
+            return prepare_response_object(
+                request.id,
+                task,
+                (Task,),
+                CancelTaskSuccessResponse,
+                CancelTaskResponse,
+            )
+
+        return CancelTaskResponse(
+            root=JSONRPCErrorResponse(id=request.id, error=TaskNotFoundError())
+        )
+
     async def on_resubscribe_to_task(
         self,
         request: TaskResubscriptionRequest,
@@ -335,15 +339,6 @@ async def on_get_task(
             task = await self.request_handler.on_get_task(
                 request.params, context
             )
-            if task:
-                return prepare_response_object(
-                    request.id,
-                    task,
-                    (Task,),
-                    GetTaskSuccessResponse,
-                    GetTaskResponse,
-                )
-            raise ServerError(error=TaskNotFoundError())  # noqa: TRY301
         except ServerError as e:
             return GetTaskResponse(
                 root=JSONRPCErrorResponse(
@@ -351,6 +346,19 @@ async def on_get_task(
                 )
             )
 
+        if task:
+            return prepare_response_object(
+                request.id,
+                task,
+                (Task,),
+                GetTaskSuccessResponse,
+                GetTaskResponse,
+            )
+
+        return GetTaskResponse(
+            root=JSONRPCErrorResponse(id=request.id, error=TaskNotFoundError())
+        )
+
     async def list_push_notification_config(
         self,
         request: ListTaskPushNotificationConfigRequest,