apache/beam · error

could not read request body

Error message

could not read request body: %w

What it means

Error built in the jobCancelHandler's ServeHTTP when io.ReadAll on the request body fails (client disconnect, connection reset, oversized body rejected). The handler wraps the underlying I/O error and returns it to the HTTP client as a 400 Bad Request response.

Solutions

1. Retry the cancel request with a well-formed HTTP client and a non-empty body
2. Ensure no proxy/client truncates the request body

When it happens

Trigger: Thrown at sdks/go/pkg/beam/runners/prism/internal/web/web.go:389 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/f68abc6386cfaa0c. Report an issue: GitHub.

Appendix: source

Thrown at sdks/go/pkg/beam/runners/prism/internal/web/web.go:389

}

type jobCancelHandler struct {
	Jobcli jobpb.JobServiceClient
}

type cancelJobRequest struct {
	JobID string `json:"job_id"`
}

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 {

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