XTLS/Xray-core · error

failed to create UDP connection

Error message

failed to create UDP connection

What it means

Error "failed to create UDP connection" thrown in XTLS/Xray-core.

Source

Thrown at proxy/socks/client.go:149

		}
	}, p.Timeouts.ConnectionIdle)

	var requestFunc func() error
	var responseFunc func() error
	if request.Command == protocol.RequestCommandTCP {
		requestFunc = func() error {
			defer timer.SetTimeout(p.Timeouts.DownlinkOnly)
			return buf.Copy(link.Reader, buf.NewWriter(conn), buf.UpdateActivity(timer))
		}
		responseFunc = func() error {
			ob.CanSpliceCopy = 1
			defer timer.SetTimeout(p.Timeouts.UplinkOnly)
			return buf.Copy(buf.NewReader(conn), link.Writer, buf.UpdateActivity(timer))
		}
	} else if request.Command == protocol.RequestCommandUDP {
		udpConn, err := dialer.Dial(ctx, udpRequest.Destination())
		if err != nil {
			return errors.New("failed to create UDP connection").Base(err)
		}
		defer udpConn.Close()
		requestFunc = func() error {
			defer timer.SetTimeout(p.Timeouts.DownlinkOnly)
			writer := &UDPWriter{Writer: udpConn, Request: request}
			return buf.Copy(link.Reader, writer, buf.UpdateActivity(timer))
		}
		responseFunc = func() error {
			ob.CanSpliceCopy = 1
			defer timer.SetTimeout(p.Timeouts.UplinkOnly)
			reader := &UDPReader{Reader: udpConn}
			return buf.Copy(reader, link.Writer, buf.UpdateActivity(timer))
		}
	}

	if newCtx != nil {
		ctx = newCtx
	}

View on GitHub (pinned to 7d214f8b09)

When it happens

Trigger: Thrown at proxy/socks/client.go:149 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/9d3588cfb85d99ba. Report an issue: GitHub.