siyuan-note/siyuan · error

missing jsonrpc field

Error message

missing jsonrpc field

What it means

JsonRpcRequest.UnmarshalJSON validates incoming JSON-RPC 2.0 messages before dispatch. The 'jsonrpc' member is mandatory and must be exactly the supported version string; when the raw message lacks the jsonrpc field entirely, unmarshalling fails with 'missing jsonrpc field'. This enforces the JSON-RPC 2.0 spec requirement that every request carry a jsonrpc member.

Solutions

1. Add "jsonrpc": "2.0" to every request body
2. Verify the exact payload sent with a network capture or by logging the raw body before unmarshal
3. If using a client library, configure the JSON-RPC 2.0 mode rather than raw JSON posting
4. Retest with a known-good minimal request: {"jsonrpc":"2.0","method":"ping","id":1}

Example fix

// before
{"method": "ping", "id": 1}
// after
{"jsonrpc": "2.0", "method": "ping", "id": 1}

function buildRpcRequest(method, params, id) { return { jsonrpc: "2.0", method, ...(params !== undefined ? { params } : {}), ...(id !== undefined ? { id } : {}) }; }

const hasJsonRpcField = (body) => body && typeof body === "object" && typeof body.jsonrpc === "string";

try { return await rpcSend(payload); } catch (e) { if (String(e).includes("missing jsonrpc field")) { console.error("payload sent:", JSON.stringify(payload)); } throw e; }

When it happens

Trigger: Posting a JSON body to the plugin RPC endpoint without a "jsonrpc" key, e.g. {"method":"x","id":1}; clients built for JSON-RPC 1.0 or ad-hoc protocols omitting the field; hand-crafted curl/test payloads.

Common situations: Developers testing the RPC endpoint with curl or Postman using a minimal body; custom MCP/JSON-RPC clients that forgot the version field; middleware stripping unknown fields from payloads.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• invalid id field: must be string, number, null or omitted
• invalid jsonrpc version
• invalid jsonrpc version
• missing method field
• RPC call requires a request or error

AI-assisted analysis of siyuan-note/siyuan@9f775e8a12 (2026-09-19). Data as JSON: /api/errors/ab679e8f81dad770. Report an issue: GitHub.

Appendix: source

Thrown at kernel/plugin/rpc.go:113

}

func (r *JsonRpcRequest) UnmarshalJSON(data []byte) error {
	decoder := json.NewDecoder(bytes.NewReader(data))
	// decoder.DisallowUnknownFields() // Reject unknown fields violates the JSON-RPC spec
	type JsonRpcRequestObject struct {
		JsonRpc util.Optional[string] `json:"jsonrpc"`
		Method  util.Optional[string] `json:"method"`
		Params  util.Optional[any]    `json:"params"`
		ID      util.Optional[any]    `json:"id"`
	}
	request := JsonRpcRequestObject{}
	if err := decoder.Decode(&request); err != nil {
		return err
	}

	// Validate jsonrpc field
	if !request.JsonRpc.Exists {
		return fmt.Errorf("missing jsonrpc field")
	}
	if request.JsonRpc.Value != JsonRpcVersion {
		return fmt.Errorf("invalid jsonrpc version: %s", request.JsonRpc.Value)
	}

	// Validate method field
	if !request.Method.HasValue() {
		return fmt.Errorf("missing method field")
	}

	// Validate id field
	if !request.ID.Exists {
	} else if request.ID.IsNull {
	} else if _, ok := request.ID.Value.(string); ok {
	} else if _, ok := request.ID.Value.(float64); ok {
	} else {
		return fmt.Errorf("invalid id field: must be string, number, null or omitted")
	}

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