"Operation is not implemented, or supported, or enabled." While trying to create_session

[arnonshtalrid]

Hi,
After deploying an ADK agent to agent engine, running:

vertexai.init(project=PROJECT_ID, location=GOOGLE_CLOUD_LOCATION)
agent = agent_engines.get(reasoning_engine_id)
print(agent.operation_schemas())

returns:
[{'api_mode': '', 'description': 'Get a session for the given user.', 'parameters': {'required': ['user_id', 'session_id'], 'properties': {'user_id': {'type': 'string'}, 'session_id': {'type': 'string'}}, 'type': 'object'}, 'name': 'get_session'}, {'api_mode': '', 'description': 'List sessions for the given user.', 'parameters': {'required': ['user_id'], 'properties': {'user_id': {'type': 'string'}}, 'type': 'object'}, 'name': 'list_sessions'}, {'api_mode': '', 'description': 'Creates a new session.', 'parameters': {'required': ['user_id'], 'properties': {'user_id': {'type': 'string'}, 'session_id': {'nullable': True, 'type': 'string'}, 'state': {'nullable': True, 'type': 'object'}}, 'type': 'object'}, 'name': 'create_session'}, {'api_mode': '', 'description': 'Deletes a session for the given user.', 'parameters': {'required': ['user_id', 'session_id'], 'properties': {'user_id': {'type': 'string'}, 'session_id': {'type': 'string'}}, 'type': 'object'}, 'name': 'delete_session'}, {'api_mode': 'async', 'description': 'Get a session for the given user.\n\n Args:\n user_id (str):\n Required. The ID of the user.\n session_id (str):\n Required. The ID of the session.\n **kwargs (dict[str, Any]):\n Optional. Additional keyword arguments to pass to the\n session service.\n\n Returns:\n Session: The session instance (if any). It returns None if the\n session is not found.\n\n Raises:\n RuntimeError: If the session is not found.\n ', 'parameters': {'required': ['user_id', 'session_id'], 'properties': {'user_id': {'type': 'string'}, 'session_id': {'type': 'string'}}, 'type': 'object'}, 'name': 'async_get_session'}, {'api_mode': 'async', 'description': 'List sessions for the given user.\n\n Args:\n user_id (str):\n Required. The ID of the user.\n **kwargs (dict[str, Any]):\n Optional. Additional keyword arguments to pass to the\n session service.\n\n Returns:\n ListSessionsResponse: The list of sessions.\n ', 'parameters': {'required': ['user_id'], 'properties': {'user_id': {'type': 'string'}}, 'type': 'object'}, 'name': 'async_list_sessions'}, {'api_mode': 'async', 'description': 'Creates a new session.\n\n Args:\n user_id (str):\n Required. The ID of the user.\n session_id (str):\n Optional. The ID of the session. If not provided, an ID\n will be be generated for the session.\n state (dict[str, Any]):\n Optional. The initial state of the session.\n **kwargs (dict[str, Any]):\n Optional. Additional keyword arguments to pass to the\n session service.\n\n Returns:\n Session: The newly created session instance.\n ', 'parameters': {'required': ['user_id'], 'properties': {'user_id': {'type': 'string'}, 'session_id': {'nullable': True, 'type': 'string'}, 'state': {'nullable': True, 'type': 'object'}}, 'type': 'object'}, 'name': 'async_create_session'}, {'api_mode': 'async', 'description': 'Deletes a session for the given user.\n\n Args:\n user_id (str):\n Required. The ID of the user.\n session_id (str):\n Required. The ID of the session.\n **kwargs (dict[str, Any]):\n Optional. Additional keyword arguments to pass to the\n session service.\n ', 'parameters': {'required': ['user_id', 'session_id'], 'properties': {'user_id': {'type': 'string'}, 'session_id': {'type': 'string'}}, 'type': 'object'}, 'name': 'async_delete_session'}, {'api_mode': 'stream', 'description': 'Streams responses from the ADK application in response to a message.\n\n Args:\n message (Union[str, Dict[str, Any]]):\n Required. The message to stream responses for.\n user_id (str):\n Required. The ID of the user.\n session_id (str):\n Optional. The ID of the session. If not provided, a new\n session will be created for the user.\n **kwargs (dict[str, Any]):\n Optional. Additional keyword arguments to pass to the\n runner.\n\n Yields:\n The output of querying the ADK application.\n ', 'parameters': {'required': ['message', 'user_id'], 'properties': {'user_id': {'type': 'string'}, 'message': {'anyOf': [{'type': 'string'}, {'additionalProperties': True, 'type': 'object'}]}, 'session_id': {'nullable': True, 'type': 'string'}}, 'type': 'object'}, 'name': 'stream_query'}, {'api_mode': 'stream', 'description': None, 'parameters': {'required': ['request_json'], 'properties': {'request_json': {'type': 'string'}}, 'type': 'object'}, 'name': 'streaming_agent_run_with_events'}, {'api_mode': 'async_stream', 'description': 'Streams responses asynchronously from the ADK application.\n\n Args:\n message (str):\n Required. The message to stream responses for.\n user_id (str):\n Required. The ID of the user.\n session_id (str):\n Optional. The ID of the session. If not provided, a new\n session will be created for the user.\n **kwargs (dict[str, Any]):\n Optional. Additional keyword arguments to pass to the\n runner.\n\n Yields:\n Event dictionaries asynchronously.\n ', 'parameters': {'required': ['message', 'user_id'], 'properties': {'user_id': {'type': 'string'}, 'message': {'anyOf': [{'type': 'string'}, {'additionalProperties': True, 'type': 'object'}]}, 'session_id': {'nullable': True, 'type': 'string'}}, 'type': 'object'}, 'name': 'async_stream_query'}]

Trying to create a session with:
session = agent.create_session(user_id="testuser")

returns:
{\"detail\":\"Agent Engine Error: An error occurred during invocation. Exception: Failed to create session.\\nRequest Data: {\'user_id\': \'testuser\'}\"}", grpc_status:9}

With curl:

 {
    "error": {
        "code": 501,
        "message": "Operation is not implemented, or supported, or enabled.",
        "status": "UNIMPLEMENTED"
    }
}

Im using the latest google-cloud-aiplatform[agent_engines,adk] and I can see the agent in gcp console agent engine UI.
Any idea what's wrong?

[cbpalumbi]

Try passing the app name as a parameter to create_session along with the user_id.

[Oximus2025]

Had a similar issue fixed by changing the region deployment from west-europe1 to us-central1 where Sessions are available