Repository navigation
Response parsing errors after OAuth flow #1173
Description
Initial Checks
- I confirm that I'm using the latest version of MCP Python SDK
- I confirm that I searched for my issue in https://github.com/modelcontextprotocol/python-sdk/issues before opening this issue
Description
The changes in #1061 overwrite the incoming request object to async_auth_flow with the request returned by self._create_oauth_metadata_request(url).
discovery_urls = self._get_discovery_urls()
for url in discovery_urls:
request = self._create_oauth_metadata_request(url)
response = yield requestAfter the auth flow occurs and the (overwritten) request is made, the client tries to parse the result. But the result is OAuth metadata, not a JSONRPC response as expected.
Example errors:
2025-07-18 15:56:35,124 - ERROR - Error parsing JSON response
Traceback (most recent call last):
File "/src/python/.venv/lib/python3.11/site-packages/mcp/client/streamable_http.py", line 302, in _handle_json_response
message = JSONRPCMessage.model_validate_json(content)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/src/python/.venv/lib/python3.11/site-packages/pydantic/main.py", line 746, in model_validate_json
return cls.__pydantic_validator__.validate_json(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
pydantic_core._pydantic_core.ValidationError: 11 validation errors for JSONRPCMessage
JSONRPCRequest.method
Field required [type=missing, input_value={'authorization_endpoint'...code', 'refresh_token']}, input_type=dict]
For further information visit https://errors.pydantic.dev/2.11/v/missing
Example Code
Python & MCP Python SDK
MCP 1.12.0
Activity
clareliguori commentedon Jul 22, 2025
Can we get a patch release for the fix? This seems to have broken OAuth for most use cases
ihrpr commentedon Jul 22, 2025
done!