kubernetes/kops · error

error reading response for %q: %v

Error message

error reading response for %q: %v

What it means

After a successful HTTP response, readHTTPLocation reads the body with io.ReadAll. If reading the body fails mid-stream (connection reset, unexpected EOF, chunked-encoding break) the error is wrapped as 'error reading response for <url>'. Like the fetch error, this is a retryable condition inside the backoff loop.

Source

Thrown at util/pkg/vfs/context.go:272

	done, err := RetryWithBackoff(opts.backoff, func() (bool, error) {
		klog.V(4).Infof("Performing HTTP request: GET %s", httpURL)
		req, err := http.NewRequest("GET", httpURL, nil)
		if err != nil {
			return false, err
		}
		for k, v := range httpHeaders {
			req.Header.Add(k, v)
		}
		response, err := http.DefaultClient.Do(req)
		if response != nil {
			defer response.Body.Close()
		}
		if err != nil {
			return false, fmt.Errorf("error fetching %q: %v", httpURL, err)
		}
		body, err = io.ReadAll(response.Body)
		if err != nil {
			return false, fmt.Errorf("error reading response for %q: %v", httpURL, err)
		}
		if response.StatusCode == 404 {
			// We retry on 404s in case of eventual consistency
			return false, os.ErrNotExist
		}
		if response.StatusCode >= 500 && response.StatusCode <= 599 {
			// Retry on 5XX errors
			return false, fmt.Errorf("unexpected response code %q for %q: %v", response.Status, httpURL, string(body))
		}

		if response.StatusCode == 200 {
			return true, nil
		}

		// Don't retry on other errors
		return true, fmt.Errorf("unexpected response code %q for %q: %v", response.Status, httpURL, string(body))
	})
	if err != nil {

View on GitHub (pinned to 4c8573c808)

Solutions

1. Simply retry - the built-in exponential backoff (5 steps) usually rides out transient resets
2. Check for proxy/LB idle timeout limits and raise them for the target URL
3. Test with `curl -v --raw <url>` to reproduce truncation and identify the terminating hop
4. Provide the file over a more reliable host/CDN if the server repeatedly resets

Example fix

// before
wait.Backoff{Duration: 500 * time.Millisecond, Factor: 2, Steps: 5} // may exhaust on flaky links
// after
vfs.WithBackoff(wait.Backoff{Duration: time.Second, Factor: 2, Steps: 10, Cap: 30 * time.Second})

// no pre-call validation exists for mid-body truncation; rely on retries and integrity checks
func bodyReadSafe(loc string) error { return nil }

err := wait.ExponentialBackoff(wait.Backoff{Duration: time.Second, Factor: 2, Steps: 6}, func() (bool, error) {
	_, err := vfs.Context.ReadFile(loc)
	if err != nil && strings.Contains(err.Error(), "error reading response") {
		return false, nil // truncated body - retry
	}
	return err == nil, err
})

When it happens

Trigger: ReadFile over http(s) where the TCP connection drops while the body is being read, a proxy/LB truncates the response, or the server closes the connection before finishing the chunked body.

Common situations: Unstable networks or VPN drops mid-transfer; load balancers with short idle timeouts killing large downloads; misbehaving proxies stripping/truncating chunked responses.

Related errors

• reading primary MAC address from ec2 metadata: %w
• downloading %q: %w
• reading body %q: %w
• error reading tag file %q: %v
• droplet metadata returned non-200 status code: %d

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/4e658e79f7e54abc. Report an issue: GitHub.