adapter name is required (use --adapt flag or leave unspecif

Error message

adapter name is required (use --adapt flag or leave unspecified for default)

What it means

Error "adapter name is required (use --adapt flag or leave unspecified for default)" thrown in caddyserver/caddy.

Source

Thrown at cmd/commandfuncs.go:576

	var err error
	configFlag, err = configFileWithRespectToDefault(caddy.Log(), configFlag)
	if err != nil {
		return caddy.ExitCodeFailedStartup, err
	}
	if configFlag == "" {
		return caddy.ExitCodeFailedStartup,
			fmt.Errorf("input file required when there is no Caddyfile in current directory (use --config flag)")
	}

	// load all additional envs as soon as possible
	err = handleEnvFileFlag(fl)
	if err != nil {
		return caddy.ExitCodeFailedStartup, err
	}

	if adapterFlag == "" {
		return caddy.ExitCodeFailedStartup,
			fmt.Errorf("adapter name is required (use --adapt flag or leave unspecified for default)")
	}

	cfgAdapter := caddyconfig.GetAdapter(adapterFlag)
	if cfgAdapter == nil {
		return caddy.ExitCodeFailedStartup,
			fmt.Errorf("unrecognized config adapter: %s", adapterFlag)
	}

	var input []byte
	// read from stdin if the file name is "-"
	if configFlag == "-" {
		input, err = io.ReadAll(os.Stdin)
	} else {
		input, err = os.ReadFile(configFlag)
	}
	if err != nil {
		return caddy.ExitCodeFailedStartup,
			fmt.Errorf("reading input file: %v", err)

View on GitHub (pinned to 50e54ee279)

Solutions

Specify the adapter name with --adapter, or omit it to use the default 'caddyfile' adapter.

When it happens

Trigger: Thrown at cmd/commandfuncs.go:576 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of caddyserver/caddy@50e54ee279 (2026-08-15). Data as JSON: /api/errors/4cf7de1a36d7f333. Report an issue: GitHub.