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Debugging Model Context Protocol · in the page docs/draft/tools/debugging …protocol versions the server supports. An `UnsupportedProtocolVersionError` (`-32022`) lists the server's supported versions in its `data` field 5. Check the [per-request `_meta` fields](/spe… Understanding Authorization in MCP Model Context Protocol · in the page docs/draft/tutorials/security/authorization …that list straight in raises a pydantic # ValidationError that the broad `except` below turns into a # silent 401. We already confirmed this server's resource i… SEP-2575: Make MCP Stateless Model Context Protocol · in the page seps/2575-stateless-mcp …_PROTOCOL_VERSION = -32022; export interface UnsupportedProtocolVersionError extends Omit< JSONRPCErrorResponse, "error" > { error: Error & { code: typeof UNSUPPORTED_PROTOCOL_VERSION;… Overview Model Context Protocol · in the page specification/2026-07-28/basic/index …colVersion`](/specification/2026-07-28/schema#unsupportedprotocolversionerror) | Codes defined by earlier protocol versions remain reserved and will not be reused. Implementations of this protocol ve… stdio Model Context Protocol · in the page specification/2026-07-28/basic/transports/stdio …recognized modern JSON-RPC error such as [`UnsupportedProtocolVersionError`][unsupported-version]: the server is modern but does not support the requested version. Use one of the versions in it… Streamable HTTP Model Context Protocol · in the page specification/2026-07-28/basic/transports/streamable-http …UST** respond with `400 Bad Request` and an [`UnsupportedProtocolVersionError`][unsupported-version] listing its supported versions. See [Versioning: Protocol Version Negotiation][lifecycle-version] f… Versioning and Compatibility Model Context Protocol · in the page specification/2026-07-28/basic/versioning …version unsupported Server-->>Client: UnsupportedProtocolVersionError Note over Client,Server: Client retries with a mutually supported version end ``` ## Terminology This page u… Key Changes Model Context Protocol · in the page specification/2026-07-28/changelog …ocol/serverInfo`). Version mismatches return `UnsupportedProtocolVersionError` ([SEP-2575](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2575)). 3. Add `server/discover`: servers… Schema Reference Model Context Protocol · in the page specification/2026-07-28/schema …equested version, it MUST return an <a href="#unsupportedprotocolversionerror" class="tsd-kind-interface">UnsupportedProtocolVersionError</a>.</p> </div></section> <section class="tsd-panel tsd-member… Discovery Model Context Protocol · in the page specification/2026-07-28/server/discover …client may invoke any RPC inline and handle [`UnsupportedProtocolVersionError`](/specification/2026-07-28/schema#unsupportedprotocolversionerror) if the server does not support the requested version.… Overview Model Context Protocol · in the page specification/draft/basic/index …ProtocolVersion`](/specification/draft/schema#unsupportedprotocolversionerror) | Codes defined by earlier protocol versions remain reserved and will not be reused. Implementations of this protocol ve… stdio Model Context Protocol · in the page specification/draft/basic/transports/stdio …recognized modern JSON-RPC error such as [`UnsupportedProtocolVersionError`][unsupported-version]: the server is modern but does not support the requested version. Use one of the versions in it… Streamable HTTP Model Context Protocol · in the page specification/draft/basic/transports/streamable-http …UST** respond with `400 Bad Request` and an [`UnsupportedProtocolVersionError`][unsupported-version] listing its supported versions. See [Versioning: Protocol Version Negotiation][lifecycle-version] f… Versioning and Compatibility Model Context Protocol · in the page specification/draft/basic/versioning …version unsupported Server-->>Client: UnsupportedProtocolVersionError Note over Client,Server: Client retries with a mutually supported version end ``` ## Terminology This page u… Schema Reference Model Context Protocol · in the page specification/draft/schema …equested version, it MUST return an <a href="#unsupportedprotocolversionerror" class="tsd-kind-interface">UnsupportedProtocolVersionError</a>.</p> </div></section> <section class="tsd-panel tsd-member… Discovery Model Context Protocol · in the page specification/draft/server/discover …client may invoke any RPC inline and handle [`UnsupportedProtocolVersionError`](/specification/draft/schema#unsupportedprotocolversionerror) if the server does not support the requested version. Howev…