XTLS/Xray-core · error

default route interface is not usable

Error message

default route interface is not usable

What it means

Error "default route interface is not usable" thrown in XTLS/Xray-core.

Source

Thrown at proxy/tun/tun_darwin.go:561

	case *route.Inet6Addr:
		mask, ok := message.Addrs[unix.RTAX_NETMASK].(*route.Inet6Addr)
		if !ok || destination.IP != netip.IPv6Unspecified().As16() {
			return 0, false
		}
		ones, bits := net.IPMask(mask.IP[:]).Size()
		return unix.AF_INET6, ones == 0 && bits == 128
	default:
		return 0, false
	}
}

func usableDarwinInterface(index int) (*net.Interface, error) {
	iface, err := net.InterfaceByIndex(index)
	if err != nil {
		return nil, err
	}
	if iface.Flags&net.FlagUp == 0 || iface.Flags&net.FlagLoopback != 0 {
		return nil, errors.New("default route interface is not usable")
	}
	return iface, nil
}

func (t *DarwinTun) setSystemRoutes() error {
	routes, err := buildDarwinSystemRoutes(t.options.AutoSystemRoutingTable)
	if err != nil {
		return err
	}
	if len(routes) == 0 {
		return nil
	}

	tunIndex, err := t.Index()
	if err != nil {
		return err
	}
	for _, destination := range routes {

View on GitHub (pinned to 7d214f8b09)

When it happens

Trigger: Thrown at proxy/tun/tun_darwin.go:561 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of XTLS/Xray-core@7d214f8b09 (2026-08-15). Data as JSON: /api/errors/628326a23f7a324b. Report an issue: GitHub.