XTLS/Xray-core · error

failed to decode request header addons

Error message

failed to decode request header addons

What it means

Error "failed to decode request header addons" thrown in XTLS/Xray-core.

Source

Thrown at proxy/vless/encoding/encoding.go:105

			buffer.Clear()
			if _, err := buffer.ReadFullFrom(reader, 16); err != nil {
				return nil, nil, nil, false, errors.New("failed to read request user id").Base(err)
			}
			copy(id[:], buffer.Bytes())
		}

		if request.User = validator.Get(id); request.User == nil {
			u := uuid.UUID(id)
			return nil, nil, nil, isfb, errors.New("invalid request user id: " + u.String())
		}

		if isfb {
			first.Advance(17)
		}

		requestAddons, err := DecodeHeaderAddons(&buffer, reader)
		if err != nil {
			return nil, nil, nil, false, errors.New("failed to decode request header addons").Base(err)
		}

		buffer.Clear()
		if _, err := buffer.ReadFullFrom(reader, 1); err != nil {
			return nil, nil, nil, false, errors.New("failed to read request command").Base(err)
		}

		request.Command = protocol.RequestCommand(buffer.Byte(0))
		switch request.Command {
		case protocol.RequestCommandMux:
			request.Address = net.DomainAddress("v1.mux.cool")
		case protocol.RequestCommandRvs:
			request.Address = net.DomainAddress("v1.rvs.cool")
		case protocol.RequestCommandTCP, protocol.RequestCommandUDP:
			if addr, port, err := addrParser.ReadAddressPort(&buffer, reader); err == nil {
				request.Address = addr
				request.Port = port
			}

View on GitHub (pinned to 7d214f8b09)

When it happens

Trigger: Thrown at proxy/vless/encoding/encoding.go:105 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

AI-assisted analysis of XTLS/Xray-core@7d214f8b09 (2026-08-15). Data as JSON: /api/errors/1119114f2578c886. Report an issue: GitHub.