XTLS/Xray-core · error

unknown type

Error message

unknown type

What it means

The JSON config loader's default switch branch: it was invoked with an input that is neither cmdarg.Arg (the string-slice of file paths Xray passes from the CLI) nor io.Reader. This is an API-misuse error for code that calls core.LoadConfig programmatically; the CLI itself never triggers it. There is no Base cause — the type is simply unsupported.

Source

Thrown at main/json/json.go:53

						// This ensure even if the muti-json parser do not support a setting,
						// It is still respected automatically for the first configure file
						*cf = *c
						continue
					}
					cf.Override(c, arg)
				}
				return cf.Build()
			case io.Reader:
				if serial.UseStrictJSON {
					cfg, err := serial.DecodeJSONConfigStrict(v)
					if err != nil {
						return nil, err
					}
					return cfg.Build()
				}
				return serial.LoadJSONConfig(v)
			default:
				return nil, errors.New("unknown type")
			}
		},
	}))
}

View on GitHub (pinned to 7d214f8b09)

Solutions

1. Convert to cmdarg.Arg before calling: cmdarg.Arg is just []string, so wrap it
2. If you have stream content, pass an io.Reader (bytes.NewReader(data)) instead
3. Prefer the high-level core.LoadConfig(format, file, input) API, which handles accepted types

Example fix

// before
c, err := core.LoadConfig("json", nil, []string{"/etc/xray/config.json"}) // -> unknown type

// after
import "github.com/xtls/xray-core/main/cmdarg"
c, err := core.LoadConfig("json", nil, cmdarg.Arg{"/etc/xray/config.json"})

if _, ok := input.(cmdarg.Arg); !ok {
    if r, ok := input.(io.Reader); !ok { input = strings.NewReader(string(input.(string))) }
}

func isSupportedLoaderInput(v interface{}) bool {
    switch v.(type) {
    case cmdarg.Arg, io.Reader: return true
    default: return false
    }
}

if !isSupportedLoaderInput(input) { return fmt.Errorf("pass cmdarg.Arg or io.Reader, got %T", input) }

When it happens

Trigger: Calling the registered Loader (via core.LoadConfig("json", ...)) with e.g. a []string instead of cmdarg.Arg, a *os.File, a byte slice, or any other type.

Common situations: Embedding Xray as a library and passing a raw string or []string of paths; wrapping the loader with a custom front-end that reads config into memory and hands over the wrong type.

Related errors

• no valid FakeDNS config
• failed to get outbound handler with tag: ${tag}
• existing tag found: ${tag}
• bridge tag is empty
• bridge domain is empty

AI-assisted analysis of XTLS/Xray-core@7d214f8b09 (2026-08-15). Data as JSON: /api/errors/b40875b35f7006fd. Report an issue: GitHub.