What causes "Error %s: %s (HTTP %d)" in mislav/hub?

Note the HTTP code in the message: retry on 5xx after a short delay (usually transient).

Error %s: %s (HTTP %d)

Error message

Error %s: %s (HTTP %d)

What it means

Also from checkStatus, this variant fires when the HTTP request completed but with an unexpected status code AND the response body could not be parsed into a structured error (response.ErrorInfo() failed). The library then reports the raw error text plus the HTTP status code, e.g. 'Error creating pull request: ... (HTTP 502)'.

Source

Thrown at github/client.go:1206

		return GitHubHost
	case "api.github.localhost":
		return "github.localhost"
	default:
		return host
	}
}

func checkStatus(expectedStatus int, action string, response *simpleResponse, err error) error {
	if err != nil {
		errStr := err.Error()
		if urlErr, isURLErr := err.(*url.Error); isURLErr {
			errStr = fmt.Sprintf("%s %s: %s", urlErr.Op, urlErr.URL, urlErr.Err)
		}
		return fmt.Errorf("Error %s: %s", action, errStr)
	} else if response.StatusCode != expectedStatus {
		errInfo, err := response.ErrorInfo()
		if err != nil {
			return fmt.Errorf("Error %s: %s (HTTP %d)", action, err.Error(), response.StatusCode)
		}
		return FormatError(action, errInfo)
	}
	return nil
}

// FormatError annotates an HTTP response error with user-friendly messages
func FormatError(action string, err error) error {
	if e, ok := err.(*errorInfo); ok {
		return formatError(action, e)
	}
	return err
}

func formatError(action string, e *errorInfo) error {
	var reason string
	if s := strings.SplitN(e.Response.Status, " ", 2); len(s) >= 2 {
		reason = strings.TrimSpace(s[1])

View on GitHub (pinned to 5c547ed804)

Solutions

Note the HTTP code in the message: retry on 5xx after a short delay (usually transient).
Inspect the raw response (curl the same endpoint) to see the non-JSON body.
If a proxy is intercepting, bypass it or fix its configuration for api.github.com.
Check the GitHub status page for ongoing incidents.

Defensive patterns

Strategy: retry

Type guard

func isUnexpectedStatus(err error) bool {
    return strings.Contains(err.Error(), "(HTTP ")
}

Try / catch

if m := httpStatusRe.FindStringSubmatch(err.Error()); m != nil {
    code, _ := strconv.Atoi(m[1])
    if code >= 500 { backoffAndRetry() }
}

Prevention

Retry 5xx responses with backoff — they are usually transient.
Bypass or fix HTML-returning proxies for api.github.com.
Watch the GitHub status page; fail fast during incidents.
On enterprise instances, verify the appliance health before API calls.

When it happens

Trigger: Server returned a status != expectedStatus with a body that isn't the expected JSON error format: HTML error pages from proxies/load balancers, 502/503/504 from GitHub, or empty bodies on 4xx/5xx.

Common situations: GitHub incident causing 5xx responses; a corporate proxy returning an HTML block page; hitting a misconfigured enterprise GitHub instance returning non-JSON errors; rate-limit pages served as HTML.

Related errors

AI-assisted analysis of mislav/hub@5c547ed804 (2026-09-01). Data as JSON: /api/errors/84c83511e79b52e7. Report an issue: GitHub.