fatedier/frp · error

invalid transport.wireProtocol, optional values are %v

Error message

invalid transport.wireProtocol, optional values are %v

What it means

transport.wireProtocol is not in SupportedWireProtocols. The wire protocol selects the framing/algebra over the transport (e.g. "legacy" yamux-style framing vs alternatives); an unrecognized value is rejected at config validation time with the allowed list in the message.

Source

Thrown at pkg/config/v1/validation/client.go:172

	if !lo.FromPtr(c.TLS.Enable) {
		checkTLSConfig := func(name string, value string) Warning {
			if value != "" {
				return fmt.Errorf("%s is invalid when transport.tls.enable is false", name)
			}
			return nil
		}

		warnings = AppendError(warnings, checkTLSConfig("transport.tls.certFile", c.TLS.CertFile))
		warnings = AppendError(warnings, checkTLSConfig("transport.tls.keyFile", c.TLS.KeyFile))
		warnings = AppendError(warnings, checkTLSConfig("transport.tls.trustedCaFile", c.TLS.TrustedCaFile))
	}

	if !slices.Contains(SupportedTransportProtocols, c.Protocol) {
		errs = AppendError(errs, fmt.Errorf("invalid transport.protocol, optional values are %v", SupportedTransportProtocols))
	}
	if !slices.Contains(SupportedWireProtocols, c.WireProtocol) {
		errs = AppendError(errs, fmt.Errorf("invalid transport.wireProtocol, optional values are %v", SupportedWireProtocols))
	}
	return warnings, errs
}

func validateIncludeFiles(files []string) (Warning, error) {
	var errs error
	for _, f := range files {
		absDir, err := filepath.Abs(filepath.Dir(f))
		if err != nil {
			errs = AppendError(errs, fmt.Errorf("include: parse directory of %s failed: %v", f, err))
			continue
		}
		if _, err := os.Stat(absDir); os.IsNotExist(err) {
			errs = AppendError(errs, fmt.Errorf("include: directory of %s not exist", f))
		}
	}
	return nil, errs
}

View on GitHub (pinned to 6c8a8d0a97)

Solutions

1. Use one of the values listed in the error message (commonly "legacy")
2. Remove transport.wireProtocol to use the default
3. Upgrade (or align) frpc/frps versions so both ends support the chosen wire protocol

Example fix

# before
[transport]
wireProtocol = "smux"

# after
[transport]
wireProtocol = "legacy"

func validWireProtocol(w string) bool {
    return slices.Contains(validation.SupportedWireProtocols, w)
}

When it happens

Trigger: transport.wireProtocol explicitly set to a string outside the supported set — e.g. "smux", "http2", or a misspelling of a valid value like "legcy".

Common situations: Experimenting with newer multiplexing options on an older frp version that doesn't include them; typo; copying docs from a different frp branch where the enum differs.

Related errors

• invalid transport.heartbeatTimeout, heartbeat timeout should
• %s is invalid when transport.tls.enable is false
• invalid transport.protocol, optional values are %v
• exec configuration is required when type is 'exec'
• file path cannot be empty

AI-assisted analysis of fatedier/frp@6c8a8d0a97 (2026-08-15). Data as JSON: /api/errors/d67330ff306bac36. Report an issue: GitHub.