apache/beam · error

error parsing JSON: of request

Error message

error parsing JSON: %s of request: %w

What it means

Error built in jobCancelHandler.ServeHTTP when json.Unmarshal of the POST body into cancelJobRequest fails — malformed JSON, wrong types, or trailing garbage. The raw body is echoed in the message to aid debugging, and the client receives HTTP 400.

Solutions

1. Send a valid JSON object with a 'job_id' string field, e.g. {"job_id": "..."}
2. Remove trailing commas or extra data after the JSON object

When it happens

Trigger: Thrown at sdks/go/pkg/beam/runners/prism/internal/web/web.go:398 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/674a21f8dd011774. Report an issue: GitHub.

Appendix: source

Thrown at sdks/go/pkg/beam/runners/prism/internal/web/web.go:398

func (h *jobCancelHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	var cancelRequest *cancelJobRequest
	if r.Method != http.MethodPost {
		http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
		return
	}
	body, err := io.ReadAll(r.Body)
	if err != nil {
		err = fmt.Errorf("could not read request body: %w", err)
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	if len(body) == 0 {
		http.Error(w, "empty request body", http.StatusBadRequest)
		return
	}
	if err := json.Unmarshal(body, &cancelRequest); err != nil {
		err = fmt.Errorf("error parsing JSON: %s of request: %w", body, err)
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	// Forward JobId from POST body avoids direct json Unmarshall on composite types containing protobuf message types.
	resp, err := h.Jobcli.Cancel(r.Context(), &jobpb.CancelJobRequest{
		JobId: cancelRequest.JobID,
	})
	if err != nil {
		statusCode := status.Code(err)
		httpCode := http.StatusInternalServerError
		if c, ok := grpcToHttpCodes[statusCode]; ok {
			httpCode = c
		}
		err = fmt.Errorf("error Cancel(%+v) = %w", cancelRequest, err)
		http.Error(w, err.Error(), httpCode)
	}

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