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

server did not return JSON-RPC error {expected_code}

Error message

server did not return JSON-RPC error {expected_code}

What it means

Error "server did not return JSON-RPC error {expected_code}" thrown in rohitg00/ai-engineering-from-scratch.

Source

Thrown at phases/13-tools-and-protocols/31-mcp-conformance-versioning-and-operations/code/main.py:428

        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}")


def run_transcript(case: Transcript) -> CaseResult:
    evidence = redact(
        {
            "headers": case.headers,
            "request": case.request,
            "responseStatus": case.response_status,
            "responseBody": case.response_body,
        }
    )
    try:
        validate_request(case.headers, case.request, case.era)
        if "id" not in case.request:
            expected_status, expected_body = notification_http_outcome(case.request)
            if (case.response_status, case.response_body) != (expected_status, expected_body):
                raise ProtocolViolation("notification received a response body")
        elif case.response_body is None:

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:428 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/9c5ec0f0e2f69a28. Report an issue: GitHub.