docker/cli · error

invalid type for size %T

Error message

invalid type for size %T

What it means

Error "invalid type for size %T" thrown in docker/cli.

Source

Thrown at cli/compose/loader/loader.go:903

var transformHealthCheckTest TransformerFunc = func(data any) (any, error) {
	switch value := data.(type) {
	case string:
		return append([]string{"CMD-SHELL"}, value), nil
	case []any:
		return value, nil
	default:
		return value, fmt.Errorf("invalid type %T for healthcheck.test", value)
	}
}

var transformSize TransformerFunc = func(value any) (any, error) {
	switch value := value.(type) {
	case int:
		return int64(value), nil
	case string:
		return units.RAMInBytes(value)
	}
	panic(fmt.Errorf("invalid type for size %T", value))
}

var transformStringToDuration TransformerFunc = func(value any) (any, error) {
	switch value := value.(type) {
	case string:
		d, err := time.ParseDuration(value)
		if err != nil {
			return value, err
		}
		return types.Duration(d), nil
	default:
		return value, fmt.Errorf("invalid type %T for duration", value)
	}
}

func toServicePortConfigs(value string) ([]any, error) {
	// short syntax ([ip:]public:private[/proto])
	//

View on GitHub (pinned to e9452d6e78)

When it happens

Trigger: Thrown at cli/compose/loader/loader.go:903 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of docker/cli@e9452d6e78 (2026-08-01). Data as JSON: /data/errors/f15989cce3d41f5e.json. Report an issue: GitHub.