AdguardTeam/AdGuardHome · warning

interface %s has no ipv4 addresses

Error message

interface %s has no ipv4 addresses

What it means

handlePatchSettingsHTTP failed to JSON-decode the request body into ReqPatchSettingsHTTP. Like the DNS variant, this is a malformed client request: invalid JSON, wrong field types, or empty body on the HTTP-settings PATCH endpoint.

Source

Thrown at internal/aghnet/dhcp_unix.go:74

		var ip net.IP
		var maskLen int
		switch a := a.(type) {
		case *net.IPAddr:
			ip = a.IP
			maskLen, _ = ip.DefaultMask().Size()
		case *net.IPNet:
			ip = a.IP
			maskLen, _ = a.Mask.Size()
		default:
			continue
		}

		if ip = ip.To4(); ip != nil {
			return netip.PrefixFrom(netip.AddrFrom4([4]byte(ip)), maskLen), nil
		}
	}

	return netip.Prefix{}, fmt.Errorf("interface %s has no ipv4 addresses", iface.Name)
}

// checkOtherDHCPv4 sends a DHCP request to the specified network interface, and
// waits for a response for a period defined by defaultDiscoverTime.  l must not
// be nil.
func checkOtherDHCPv4(
	ctx context.Context,
	l *slog.Logger,
	iface *net.Interface,
) (ok bool, err error) {
	var subnet netip.Prefix
	if subnet, err = ifaceIPv4Subnet(iface); err != nil {
		return false, err
	}

	// Resolve broadcast addr.
	dst := netip.AddrPortFrom(BroadcastFromPref(subnet), 67).String()
	var dstAddr *net.UDPAddr

View on GitHub (pinned to b41aefbe51)

Solutions

1. Lint the JSON payload before sending
2. Check ReqPatchSettingsHTTP field types in the API docs and match them
3. Ensure proxies don't truncate bodies and Content-Type is application/json
4. Use the web UI to change settings while debugging the raw request

Example fix

// before
curl -X PATCH http://host/control/http_config -d '{"port": "80"}'
// after
curl -X PATCH http://host/control/http_config \
  -H 'Content-Type: application/json' \
  -d '{"port": 80}'

var req ReqPatchSettingsHTTP
if err := json.Unmarshal(body, &req); err != nil { return err }

func isValidPatchHTTP(body []byte) bool {
    var r ReqPatchSettingsHTTP
    return json.Unmarshal(body, &r) == nil
}

if resp.StatusCode >= 400 {
    // decode error payload; malformed JSON is caller's fault — fix body
}

When it happens

Trigger: PATCHing the HTTP/web-interface settings endpoint with syntactically invalid JSON or fields whose types don't match the expected struct (e.g. a number where a string address is expected).

Common situations: Automated scripts sending unescaped JSON; API version mismatch where field types changed; truncated request bodies behind a misconfigured proxy.

Related errors

• parsing json time: %w
• json time is nil
• interface %s has no ipv6 addresses
• invalid ip version %d
• found no dns servers in %s

AI-assisted analysis of AdguardTeam/AdGuardHome@b41aefbe51 (2026-08-27). Data as JSON: /api/errors/ce6a23f01e1d574f. Report an issue: GitHub.