modelcontextprotocol/python-sdk issues and pull requests

#1818 - fix: auto-reinitialize client session on HTTP 404

Pull Request - State: open - Opened by jayhemnani9910 about 1 month ago - 1 comment
Labels: bug, improves spec compliance, P2

#1817 - fix: cleanup resources properly on `BaseSession::_receive_loop` cleanup

Pull Request - State: open - Opened by challenger71498 about 1 month ago - 2 comments
Labels: bug, P1

#1811 - client's `read_stream_writer` open after SSE disconnection hanging `.receive()`

Issue - State: open - Opened by ivanbelenky about 2 months ago - 2 comments
Labels: bug, ready for work, P1

#1805 - Possible ressource leak / race condition in streamable_http_client

Issue - State: open - Opened by h-filzer about 2 months ago - 6 comments
Labels: bug, needs confirmation

#1795 - Make JSON-RPC ID type coercion configurable

Issue - State: open - Opened by maxisbey about 2 months ago - 1 comment
Labels: bug, v2, P3

#1784 - Fix `token_expiry_time` upon context initialization for stored tokens.

Pull Request - State: open - Opened by keurcien about 2 months ago - 1 comment
Labels: bug, auth, P1

#1727 - StreamableHTTPSessionManager returns 400 instead of 404 for unknown session ID

Issue - State: open - Opened by johnw188 2 months ago - 1 comment
Labels: bug, ready for work, P0

#1666 - fix: Fix logic that determines standard resource vs. resource template to account for context param (#1635)

Pull Request - State: open - Opened by matthew-gries 2 months ago - 2 comments
Labels: bug, breaking change, v2, P2

#1651 - Make refresh_token grant type optional in DCR handler

Pull Request - State: open - Opened by gazzadownunder 3 months ago
Labels: bug, auth, improves spec compliance

#1578 - Fix issue where client tool call hangs forever if server crashes or connection dies when using streamable-http

Pull Request - State: open - Opened by gyang-xai 3 months ago - 1 comment
Labels: bug

#1506 - fix:streamablehttp_client to raise McpError when receiving unexpected content types instead of just printing error messages.#1382

Pull Request - State: open - Opened by Wyn1996 4 months ago
Labels: bug, needs maintainer action

#1490 - Add tests for resource leak in streamable_http SSE handlers

Pull Request - State: closed - Opened by certainly-param 4 months ago - 1 comment
Labels: bug, needs maintainer action, P0

#1481 - fix: Token endpoint response for invalid_client

Pull Request - State: open - Opened by AnkeshThakur 4 months ago
Labels: bug, auth

#1477 - Test fails in a Windows system with a proxy enabled

Issue - State: closed - Opened by Chenzhen-Ye 4 months ago - 1 comment
Labels: bug, good first issue, ready for work, P3

#1472 - Test assertion fails on Chinese system locale

Issue - State: open - Opened by mingo1996 4 months ago
Labels: bug, PR welcome, ready for work, P3

#1452 - The `stdio_client` hangs indefinitely on session initialization

Issue - State: open - Opened by Shashikant86 4 months ago - 2 comments
Labels: bug, ready for work, P0

#1451 - Build failure on Python 3.14 due to outdated pydantic-core dependency

Issue - State: closed - Opened by wang93wei 4 months ago - 2 comments
Labels: bug, needs repro

#1450 - Response leak in SSE handlers

Issue - State: open - Opened by certainly-param 4 months ago - 1 comment
Labels: bug, needs repro

#1445 - MCP Python SDK Implementation Gap-13: Server Missing Token Issuer Validation

Issue - State: closed - Opened by younaman 4 months ago - 7 comments
Labels: bug, auth

#1442 - MCP Python SDK Implementation Gap-10: MCP Python SDK Client Missing Token Issuer Validation

Issue - State: closed - Opened by younaman 4 months ago
Labels: bug, good first issue, PR welcome, auth, ready for work, P0

#1441 - MCP Python SDK Implementation Gap-9: TokenVerifier lacks OAuth 2.1 Section 5.2 comprehensive token validation

Issue - State: closed - Opened by younaman 4 months ago
Labels: bug, auth, ready for work, P1

#1434 - MCP Python SDK Implementation Gap-6: HTTP requests are not enforced to include Authorization header

Issue - State: closed - Opened by younaman 4 months ago
Labels: bug, auth, ready for work, P1

#1428 - Eicitation Context request timeout via streamable-http transport "MCP error -32001: Request timed out"

Issue - State: open - Opened by longcld 4 months ago - 3 comments
Labels: bug, ready for work, P0

#1408 - Fix optional parameters in tools handling

Pull Request - State: closed - Opened by PreistlyPython 4 months ago - 2 comments
Labels: bug, needs more work, needs more eyes

#1404 - fix: set default to none for optional field without default value

Pull Request - State: closed - Opened by vincent0426 4 months ago - 4 comments
Labels: bug, needs confirmation, needs more eyes

#1385 - RequestResponder Not Cleaned Up in BaseSession _receive_loop Causing Session Memory Leak

Issue - State: closed - Opened by weblover12 5 months ago - 3 comments
Labels: bug

#1384 - fix: handle ClosedResourceError in StreamableHTTP message router

Pull Request - State: open - Opened by Edison-A-N 5 months ago - 2 comments
Labels: bug, needs maintainer action

#1382 - Cannot handle `Unexpected content type` when initializing MCP session

Issue - State: open - Opened by bystepii 5 months ago - 1 comment
Labels: bug, ready for work, P2

#1372 - fastmcp.run() runtimeerror: task group is not initialized. make sure to use run().

Issue - State: open - Opened by SinDongHwan 5 months ago - 2 comments
Labels: bug, needs repro

#1367 - Mounting a Streamable HTTP MCP endpoint on existing FastAPI app does not work

Issue - State: closed - Opened by vemonet 5 months ago - 4 comments
Labels: bug, needs confirmation

#1361 - ClientSession swallow call_tool exceptions

Issue - State: closed - Opened by mingx1998 5 months ago - 2 comments
Labels: bug, needs repro

#1355 - UTF-8 Cyrillic text is replaced with ????. I'm using streamablehttp_client

Issue - State: closed - Opened by ArthurKaplanov 5 months ago - 6 comments
Labels: bug, needs repro

#1332 - Implement consistent structuredContent handling per specification clarification

Issue - State: open - Opened by dsp-ant 5 months ago - 1 comment
Labels: bug, ready for work, P0

#1299 - fix: tool cache refresh with nested handler invocation

Pull Request - State: closed - Opened by matthicksj 6 months ago - 1 comment
Labels: bug, needs maintainer action

#1219 - _handle_stateless_request ClosedResourceError

Issue - State: open - Opened by 281743556 6 months ago - 5 comments
Labels: bug, ready for work, P0

#1135 - MCP Python SDK sessionId not maintained in browser with TypeScript SDK client

Issue - State: open - Opened by waugmeiigaxaa 7 months ago - 1 comment
Labels: bug, needs confirmation

#1129 - Tool context kwarg detection not compatible with string-valued/future annotations

Issue - State: open - Opened by dmontagu 7 months ago - 2 comments
Labels: bug, ready for work, P1

#1073 - Inconsistent Field Naming Between `outputSchema` and `model_dump`

Issue - State: closed - Opened by akolotov 7 months ago
Labels: bug, good first issue

#1072 - Errors with Streamble HTTP

Issue - State: open - Opened by pavankay 7 months ago - 7 comments
Labels: bug, needs confirmation

#1053 - Streamable HTTP transport fails when accessing MCP server on Cloud Run using sdk

Issue - State: open - Opened by sidgangs99 7 months ago - 4 comments
Labels: bug, needs confirmation

#1035 - mcp.shared.auth_utils package not available on main branch

Issue - State: closed - Opened by mellebrouwer 7 months ago - 3 comments
Labels: bug, auth, ready for work, P0

#1008 - fix: Add exception handling for POST request failures in StreamableHTTP

Pull Request - State: closed - Opened by Kulaxyz 8 months ago - 4 comments
Labels: bug, needs maintainer action

#975 - fix: catch and rethrow SSEError during SSE connection establishment

Pull Request - State: closed - Opened by zhangch-ss 8 months ago
Labels: bug

#953 - context.report_progress not sending notifications on streamable-http

Issue - State: open - Opened by abdhx 8 months ago - 4 comments
Labels: bug, ready for work, P3

#932 - `simple-tool` exiting error

Issue - State: closed - Opened by ruspaul013 8 months ago - 2 comments
Labels: bug, wontfix

#874 - Cannot break out of session.initialize() when using streamable-http

Issue - State: open - Opened by efcwetgw 8 months ago - 5 comments
Labels: bug, ready for work, P1

#775 - fix: improve misleading warning for progress callback exceptions

Pull Request - State: closed - Opened by lorenzocesconetto 9 months ago - 9 comments
Labels: bug, needs maintainer action

#589 - Chinese conversion garbled characters

Issue - State: closed - Opened by wenlia777 9 months ago - 3 comments
Labels: bug, needs confirmation

#585 - Python MCP SDK: Incorrect handling of absolute paths in SSE endpoint URLs leads to incorrect URL construction.

Issue - State: open - Opened by footuser 10 months ago - 1 comment
Labels: bug

#577 - `RuntimeError: Attempted to exit cancel scope in a different task` when cleaning up multiple MCPClient instances out-of-order

Issue - State: open - Opened by HMJiangGatech 10 months ago - 7 comments
Labels: bug, ready for work, P1

GitHub / modelcontextprotocol/python-sdk issues and pull requests