XTLS/Xray-core · error

failed to read payload length

Error message

failed to read payload length

What it means

Error "failed to read payload length" thrown in XTLS/Xray-core.

Source

Thrown at proxy/trojan/protocol.go:228

	_, err := b.ReadFrom(c)
	return buf.MultiBuffer{b}, err
}

// PacketReader is UDP Connection Reader Wrapper for trojan protocol
type PacketReader struct {
	io.Reader
}

// ReadMultiBuffer implements buf.Reader
func (r *PacketReader) ReadMultiBuffer() (buf.MultiBuffer, error) {
	addr, port, err := addrParser.ReadAddressPort(nil, r)
	if err != nil {
		return nil, errors.New("failed to read address and port").Base(err)
	}

	var lengthBuf [2]byte
	if _, err := io.ReadFull(r, lengthBuf[:]); err != nil {
		return nil, errors.New("failed to read payload length").Base(err)
	}

	remain := int(binary.BigEndian.Uint16(lengthBuf[:]))
	if remain > maxLength {
		return nil, errors.New("oversize payload")
	}

	var crlf [2]byte
	if _, err := io.ReadFull(r, crlf[:]); err != nil {
		return nil, errors.New("failed to read crlf").Base(err)
	}

	dest := net.UDPDestination(addr, port)
	var mb buf.MultiBuffer
	for remain > 0 {
		length := buf.Size
		if remain < length {
			length = remain

View on GitHub (pinned to 7d214f8b09)

When it happens

Trigger: Thrown at proxy/trojan/protocol.go:228 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/deae33f41cedae2f. Report an issue: GitHub.