What causes "Error %s: %s" in mislav/hub?

Check network connectivity to the API host (`curl -v https://api.github.com`).

Error %s: %s

Error message

Error %s: %s

What it means

checkStatus is the shared response validator for all REST calls. This error occurs when the transport itself failed (err != nil): the library wraps it as 'Error <action>: <detail>', formatting *url.Error specially as '<op> <url>: <cause>'. It means the HTTP request never completed successfully — not an unexpected HTTP status.

Source

Thrown at github/client.go:1202

func reverseNormalizeHost(host string) string {
	switch host {
	case "api.github.com":
		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
}

View on GitHub (pinned to 5c547ed804)

Solutions

Check network connectivity to the API host (`curl -v https://api.github.com`).
Configure HTTPS_PROXY/HTTP_PROXY if you're behind a proxy.
Fix TLS trust (add corporate CA to the system trust store) if the error is a certificate error.
Retry on transient timeouts; check DNS resolution if the error is 'no such host'.

Defensive patterns

Strategy: retry

Validate before calling

if _, err := net.LookupHost("api.github.com"); err != nil {
    return fmt.Errorf("cannot resolve api.github.com; check network/DNS/proxy")
}

Type guard

var urlErr *url.Error
if errors.As(err, &urlErr) { /* transport-level failure */ }

Try / catch

err := doAPICall()
if err != nil {
    var ue *url.Error
    if errors.As(err, &ue) && isTransient(ue.Err) {
        time.Sleep(backoff); retry()
    }
}

Prevention

Configure HTTPS_PROXY in proxied/CI environments.
Add corporate CAs to the trust store for TLS interception setups.
Use exponential backoff with jitter for transient network errors.
Monitor connectivity to api.github.com in health checks.

When it happens

Trigger: Network unreachable, DNS failure, TLS errors, connection refused/timeouts, or a canceled request during any API call, surfaced through checkStatus's action label (e.g. 'creating pull request').

Common situations: Working offline or behind a corporate proxy without proxy env vars configured; DNS not resolving api.github.com; self-signed/MITM proxy certificates breaking TLS; firewall blocking egress in CI.

Understand the failure class

Background: 'Something went wrong' / 'Request failed (500)' / 'HTTP error! status: 404' — what failed HTTP requests actually mean and how to find the real cause — this error's family across 28 libraries.

Related errors

AI-assisted analysis of mislav/hub@5c547ed804 (2026-09-01). Data as JSON: /api/errors/d41e53ec0ea1c6cc. Report an issue: GitHub.