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Deploy docs: reused-process runtimes (Lambda) hit the single-use session manager error, but aren't covered

Status: Open.

#3590 In modelcontextprotocol/python-sdk;

· pandayv opened on Sep 27, 2026

DirectoryResource listing uses OS path separators and unstable order

v1Affects the v1.x maintenance lineAffects the v1.x maintenance line

v2Affects the v2 line (2.x on main)Affects the v2 line (2.x on main)

Status: Open.

#3589 In modelcontextprotocol/python-sdk;

· tasnemawawde-afk opened on Sep 27, 2026

Streamable HTTP: Client mode="auto" fails on server/discover against MCPServer + uvicorn (RemoteProtocolError)

spec-2026-07-28Concerns the SDK's implementation of the 2026-07-28 MCP spec revisionConcerns the SDK's implementation of the 2026-07-28 MCP spec revision

v2Affects the v2 line (2.x on main)Affects the v2 line (2.x on main)

Status: Open.

#3588 In modelcontextprotocol/python-sdk;

· Kandeepasundaram opened on Sep 27, 2026

Streamable HTTP on Windows: after a tool raises a non-ToolError, no request is answered again (2.1.0+, 2.0.1 fine)

v2Affects the v2 line (2.x on main)Affects the v2 line (2.x on main)

Status: Open.

#3586 In modelcontextprotocol/python-sdk;

· ryanduguid opened on Sep 26, 2026

Image/Audio format= emits image/jpg, audio/mp3, audio/m4a — unregistered MIME types that disagree with the path= suffix table

v1Affects the v1.x maintenance lineAffects the v1.x maintenance line

v2Affects the v2 line (2.x on main)Affects the v2 line (2.x on main)

Status: Open.

#3585 In modelcontextprotocol/python-sdk;

· JoeyTan21 opened on Sep 26, 2026

ClientSessionGroup has no routed read_resource / get_prompt (only call_tool)

Status: Open.

#3579 In modelcontextprotocol/python-sdk;

· baselarw opened on Sep 24, 2026

ClientSessionGroup raises KeyError when connecting a server that exposes no components

v1Affects the v1.x maintenance lineAffects the v1.x maintenance line

v2Affects the v2 line (2.x on main)Affects the v2 line (2.x on main)

Status: Open.

#3578 In modelcontextprotocol/python-sdk;

· baselarw opened on Sep 24, 2026

Make Origin validation opt-in in the app factories (keep Host validation on for localhost)

Status: Open.

#3576 In modelcontextprotocol/python-sdk;

· daoluc opened on Sep 24, 2026

func_metadata raises uncaught PydanticSchemaGenerationError for Iterator/AsyncIterator tool return annotations instead of the unstructured fallback

v1Affects the v1.x maintenance lineAffects the v1.x maintenance line

v2Affects the v2 line (2.x on main)Affects the v2 line (2.x on main)

Status: Open.

#3573 In modelcontextprotocol/python-sdk;

· BlueX888 opened on Sep 23, 2026

Tool validation errors echo the rejected input value (input_value) — add a masking option or a public validation-error hook

Status: Open.

#3572 In modelcontextprotocol/python-sdk;

· panandr opened on Sep 23, 2026

OAuthClientProvider: no supported way to override endpoints or customize authorization state generation

Status: Open.

#3570 In modelcontextprotocol/python-sdk;

· dgilman-perplexity opened on Sep 23, 2026

Client transports/sessions swallow the original exception; applications cannot classify 401/403/429 transport failures

Status: Open.

#3569 In modelcontextprotocol/python-sdk;

· dgilman-perplexity opened on Sep 23, 2026