XTLS/Xray-core · error

failed to build loopback sniffing request

Error message

failed to build loopback sniffing request

What it means

Error "failed to build loopback sniffing request" thrown in XTLS/Xray-core.

Source

Thrown at proxy/loopback/loopback.go:59

		*inbound = *originInbound
	}
	inbound.Tag = l.inboundTag
	ctx = session.ContextWithInbound(ctx, inbound)

	err := l.dispatcherInstance.DispatchLink(ctx, destination, link)
	if err != nil {
		return errors.New(ctx, "failed to process loopback connection").Base(err)
	}
	return nil
}

func (l *Loopback) init(config *Config, dispatcherInstance routing.Dispatcher) error {
	l.dispatcherInstance = dispatcherInstance
	l.inboundTag = config.InboundTag
	if config.Sniffing.GetEnabled() {
		request, err := proxyman.BuildSniffingRequest(config.Sniffing)
		if err != nil {
			return errors.New("failed to build loopback sniffing request").Base(err).AtError()
		}
		l.sniffingRequest = request
	}
	return nil
}

func init() {
	common.Must(common.RegisterConfig((*Config)(nil), func(ctx context.Context, config interface{}) (interface{}, error) {
		l := new(Loopback)
		err := core.RequireFeatures(ctx, func(dispatcherInstance routing.Dispatcher) error {
			return l.init(config.(*Config), dispatcherInstance)
		})
		return l, err
	}))
}

View on GitHub (pinned to 7d214f8b09)

When it happens

Trigger: Thrown at proxy/loopback/loopback.go:59 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/37a27a7edd46f43c. Report an issue: GitHub.