grafana/k6 · error

getting response body: %w

Error message

getting response body: %w

What it means

Response.Body() first fetches the body over CDP (fetchBody, with its 5x retry loop for late-arriving data), then returns the cached bytes. This error wraps that fetch failure; the separate redirect-status guard is a distinct error, so hitting this one means the status was fine but Network.getResponseBody failed.

Source

Thrown at internal/js/modules/k6/browser/common/http.go:666

		for name, values := range r.extraHeaders {
			headers[strings.ToLower(name)] = strings.Join(values, "\n")
		}
	} else {
		for name, values := range r.headers {
			headers[strings.ToLower(name)] = strings.Join(values, "\n")
		}
	}
	r.extraHeadersMu.RUnlock()
	return headers
}

// Body returns the response body as a bytes buffer.
func (r *Response) Body() ([]byte, error) {
	if r.status >= 300 && r.status <= 399 {
		return nil, fmt.Errorf("response body is unavailable for redirect responses")
	}
	if err := r.fetchBody(); err != nil {
		return nil, fmt.Errorf("getting response body: %w", err)
	}

	r.bodyMu.RLock()
	defer r.bodyMu.RUnlock()

	return r.body, nil
}

// bodySize returns the size in bytes of the response body.
func (r *Response) bodySize() int64 {
	// Skip redirect responses
	if r.status >= 300 && r.status <= 399 {
		return 0
	}

	if err := r.fetchBody(); err != nil {
		r.logger.Debugf("Response:bodySize:fetchBody",
			"url:%s method:%s err:%s", r.url, r.request.method, err)

View on GitHub (pinned to 93accf6570)

Solutions

1. Call res.body() immediately after receiving the response object
2. Avoid reading bodies for intercepted (fulfilled) responses through this API
3. Ensure the page and context stay open until body assertions finish
4. If it happens only under load, investigate browser stability (memory, sandbox, zombie processes)

Example fix

// before
const res = await promiseOfNavigation; // stored for later
await doOtherWork();
const body = await res.body();

// after
const res = await promiseOfNavigation;
const body = await res.body(); // read as soon as it arrives
await doOtherWork();

try {
  const body = await res.body();
} catch (e) {
  if (!/getting response body/.test(String(e.message))) throw e;
  // body unavailable: page navigated/closed or fulfilled response
}

When it happens

Trigger: Calling res.body() when the body cannot be retrieved: page navigated away or closed before the read, response fulfilled via route.fulfill() with no network data, cached/service-worker responses without retrievable bodies, or the DevTools session/browser gone.

Common situations: Deferring body reads until after navigation or teardown; intercepted requests; CI flakiness where the browser drops under load; asserting on large streaming responses.

Related errors

• fetching response body: %w
• getting response body as text: %w
• errorText
• updating extra HTTP headers: %w
• updating offline mode for frame %v: %w

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/641f7631059d6bd3. Report an issue: GitHub.