rohitg00/ai-engineering-from-scratch · error · ProtocolViolation

JSON-RPC error requires integer code and string message

Error message

JSON-RPC error requires integer code and string message

What it means

Error "JSON-RPC error requires integer code and string message" thrown in rohitg00/ai-engineering-from-scratch.

Source

Thrown at phases/13-tools-and-protocols/31-mcp-conformance-versioning-and-operations/code/main.py:410

    if type(response_id) is not type(request_id) or response_id != request_id:
        raise ProtocolViolation("response id does not exactly match request id")
    has_result = "result" in response
    has_error = "error" in response
    if has_result == has_error:
        raise ProtocolViolation("response must contain exactly one of result or error")
    if has_result:
        if status != 200:
            raise ProtocolViolation("successful JSON-RPC result requires HTTP 200")
        validate_result(response["result"], era, capabilities)
        validate_method_result(request["method"], response["result"])
        return

    error = response["error"]
    if not isinstance(error, dict):
        raise ProtocolViolation("JSON-RPC error must be an object")
    code = error.get("code")
    if isinstance(code, bool) or not isinstance(code, int) or not isinstance(error.get("message"), str):
        raise ProtocolViolation("JSON-RPC error requires integer code and string message")
    expected_status = {-32020: 400, -32021: 400, -32022: 400, -32601: 404}.get(code)
    if expected_status is not None and status != expected_status:
        raise ProtocolViolation(f"JSON-RPC error {code} requires HTTP {expected_status}")


def validate_protocol_error_evidence(case: Transcript, expected_code: int) -> None:
    if case.response_body is None:
        raise ProtocolViolation("expected JSON-RPC error response is missing")
    validate_response(
        case.request,
        case.response_status,
        case.response_body,
        case.era,
        set(case.capabilities),
    )
    error = case.response_body.get("error")
    if not isinstance(error, dict) or error.get("code") != expected_code:
        raise ProtocolViolation(f"server did not return JSON-RPC error {expected_code}")

View on GitHub (pinned to 39ea8a1c6d)

When it happens

Trigger: Thrown at phases/13-tools-and-protocols/31-mcp-conformance-versioning-and-operations/code/main.py:410 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of rohitg00/ai-engineering-from-scratch@39ea8a1c6d (2026-08-26). Data as JSON: /api/errors/3ee2c71fa9ed0c96. Report an issue: GitHub.