XTLS/Xray-core · error

Config: unknown transport protocol: + p

Error message

Config: unknown transport protocol:  + p

What it means

Thrown by TransportProtocol.Build() when the configured transport protocol string does not match any known value. Accepted values include tcp/raw, mkcp/kcp, websocket, httpupgrade, splithttp/xhttp, domainsocket, hysteria; 'h2'/'h3'/'http' and 'quic' are hard-removed features and produce dedicated removal errors instead. Anything else falls through to this unknown-protocol error.

Source

Thrown at infra/conf/transport_internet.go:40

	case "kcp", "mkcp":
		return "mkcp", nil
	case "grpc":
		errors.PrintNonRemovalDeprecatedFeatureWarning("gRPC transport (with unnecessary costs, etc.)", "XHTTP stream-up H2")
		return "grpc", nil
	case "ws", "websocket":
		errors.PrintNonRemovalDeprecatedFeatureWarning("WebSocket transport (with ALPN http/1.1, etc.)", "XHTTP H2 & H3")
		return "websocket", nil
	case "httpupgrade":
		errors.PrintNonRemovalDeprecatedFeatureWarning("HTTPUpgrade transport (with ALPN http/1.1, etc.)", "XHTTP H2 & H3")
		return "httpupgrade", nil
	case "h2", "h3", "http":
		return "", errors.PrintRemovedFeatureError("HTTP transport (without header padding, etc.)", "XHTTP stream-one H2 & H3")
	case "quic":
		return "", errors.PrintRemovedFeatureError("QUIC transport (without web service, etc.)", "XHTTP stream-one H3")
	case "hysteria":
		return "hysteria", nil
	default:
		return "", errors.New("Config: unknown transport protocol: ", p)
	}
}

type StreamConfig struct {
	Address             *Address           `json:"address"`
	Port                uint16             `json:"port"`
	Method              *TransportProtocol `json:"method"`
	Network             *TransportProtocol `json:"network"`
	Security            string             `json:"security"`
	FinalMask           *FinalMask         `json:"finalmask"`
	TLSSettings         *TLSConfig         `json:"tlsSettings"`
	REALITYSettings     *REALITYConfig     `json:"realitySettings"`
	RAWSettings         *TCPConfig         `json:"rawSettings"`
	TCPSettings         *TCPConfig         `json:"tcpSettings"`
	XHTTPSettings       *SplitHTTPConfig   `json:"xhttpSettings"`
	SplitHTTPSettings   *SplitHTTPConfig   `json:"splithttpSettings"`
	KCPSettings         *KCPConfig         `json:"kcpSettings"`
	GRPCSettings        *GRPCConfig        `json:"grpcSettings"`

View on GitHub (pinned to 7d214f8b09)

Solutions

1. Correct the protocol name to a supported one: tcp, mkcp, websocket, httpupgrade, splithttp, etc.
2. If you used 'h2', 'h3', 'http' or 'quic', migrate to splithttp (XHTTP H2/H3).
3. Check for stray whitespace/case differences in the JSON value.

Example fix

// before
"network": "http"
// after
"network": "splithttp"

var known = map[string]bool{"tcp": true, "raw": true, "mkcp": true, "kcp": true, "websocket": true, "httpupgrade": true, "splithttp": true, "xhttp": true, "domainsocket": true, "hysteria": true}
if !known[strings.ToLower(p)] {
    return fmt.Errorf("unsupported transport protocol %q", p)
}

When it happens

Trigger: Setting streamSettings.network (or method) to e.g. "tls", "grpc2", "TCP" (case-sensitive where not normalized), or a typo like "websockets" triggers this during StreamConfig build.

Common situations: Typos in protocol names; using a protocol removed in this fork (plain http/quic); copying configs from a client with different protocol naming.

Related errors

• gecko: invalid min/max packet size
• invalid scheme + u.Scheme
• empty stunServers
• bridge tag is empty
• bridge domain is empty

AI-assisted analysis of XTLS/Xray-core@7d214f8b09 (2026-08-15). Data as JSON: /api/errors/ee69b6c5c852d97b. Report an issue: GitHub.