What causes "creating authentication request: %v" in glanceapp/glance?

Inspect the widget's url value for typos, missing scheme, spaces, or bad interpolation.

creating authentication request: %v

Error message

creating authentication request: %v

What it means

Returned by fetchPiholeSessionID when http.NewRequest("POST", instanceURL+"/api/auth", ...) fails before any network I/O. NewRequest fails only on an unparseable URL: unsupported scheme, control characters in the URL, or a malformed host — so this almost always means the configured URL string itself is broken.

Source

Thrown at internal/glance/widget-dns-stats.go:623

				PercentBlocked: int(float64(d.Count) / float64(statsResponse.Queries.Blocked) * 100),
			})
		}

		sort.Slice(domains, func(a, b int) bool {
			return domains[a].PercentBlocked > domains[b].PercentBlocked
		})
		stats.TopBlockedDomains = domains[:min(len(domains), 5)]
	}

	return stats, sessionID, ternary(partialContent, errPartialContent, nil)
}

func fetchPiholeSessionID(instanceURL string, client *http.Client, password string) (string, error) {
	requestBody := []byte(`{"password":"` + password + `"}`)

	request, err := http.NewRequest("POST", instanceURL+"/api/auth", bytes.NewBuffer(requestBody))
	if err != nil {
		return "", fmt.Errorf("creating authentication request: %v", err)
	}
	request.Header.Set("Content-Type", "application/json")

	response, err := client.Do(request)
	if err != nil {
		return "", fmt.Errorf("sending authentication request: %v", err)
	}
	defer response.Body.Close()

	body, err := io.ReadAll(response.Body)
	if err != nil {
		return "", fmt.Errorf("reading authentication response: %v", err)
	}

	var jsonResponse struct {
		Session struct {
			SID     string `json:"sid"`
			Message string `json:"message"`

View on GitHub (pinned to 91324e8de7)

Solutions

Inspect the widget's url value for typos, missing scheme, spaces, or bad interpolation.
Always include the scheme: http://pihole.local or https://...
Quote the URL in YAML if it contains special characters.
Test with url.Parse in Go or simply curl the same string.

Example fix

# before
url: pihole.local:80

# after
url: http://pihole.local:80

Defensive patterns

Strategy: validation

Validate before calling

u, err := url.Parse(widget.URL)
if err != nil || (u.Scheme != "http" && u.Scheme != "https") || u.Host == "" {
    return fmt.Errorf("dns-stats: url must be a valid http(s) URL, got %q", widget.URL)
}

Prevention

Always configure full URLs with scheme (http:// or https://).
Quote YAML URL values containing special characters.
Fail config validation on empty/scheme-less URLs before runtime.

When it happens

Trigger: url containing spaces or control characters, a scheme like ftp:// or missing entirely (no http://), or a password/URL concatenation producing invalid characters in the request line.

Common situations: YAML value with a trailing space or unquoted special characters; copy-pasted URL missing the scheme; environment-variable-substituted URL that rendered empty or malformed.

Understand the failure class

Authentication and authorization failures — expired tokens, bad credentials, and missing scopes.

Related errors

AI-assisted analysis of glanceapp/glance@91324e8de7 (2026-08-15). Data as JSON: /api/errors/82442e92b7b291a2. Report an issue: GitHub.