fluent/fluentd · error · ArgumentError

:list is valid only for :enum type, but #{type}: #{name}

Error message

:list is valid only for :enum type, but #{type}: #{name}

What it means

Error ":list is valid only for :enum type, but #{type}: #{name}" thrown in fluent/fluentd.

Source

Thrown at lib/fluent/config/configure_proxy.rb:238

            end
          when nil
            # ignore
          else
            raise "unknown type: #{type} for option #{key}"
          end
        end
      end

      def config_parameter_option_validate!(name, type, **kwargs, &block)
        if type.nil? && !block
          type = :string
        end
        kwargs.each_key do |key|
          case key
          when :default, :alias, :secret, :skip_accessor, :deprecated, :obsoleted, :desc
            # valid for all types
          when :list
            raise ArgumentError, ":list is valid only for :enum type, but #{type}: #{name}" if type != :enum
          when :value_type
            raise ArgumentError, ":value_type is valid only for :hash and :array, but #{type}: #{name}" if type != :hash && type != :array
          when :symbolize_keys
            raise ArgumentError, ":symbolize_keys is valid only for :hash, but #{type}: #{name}" if type != :hash
          else
            raise ArgumentError, "unknown option '#{key}' for configuration parameter: #{name}"
          end
        end
      end

      def parameter_configuration(name, type = nil, **kwargs, &block)
        config_parameter_option_validate!(name, type, **kwargs, &block)

        name = name.to_sym

        if block && type
          raise ArgumentError, "#{name}: both of block and type cannot be specified"
        elsif !block && !type

View on GitHub (pinned to dd45c6e18d)

When it happens

Trigger: Thrown at lib/fluent/config/configure_proxy.rb:238 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of fluent/fluentd@dd45c6e18d (2026-08-21). Data as JSON: /api/errors/2aa0447609def369. Report an issue: GitHub.