fluent/fluentd · error · ArgumentError

BUG: block not specified which handles connection

Error message

BUG: block not specified which handles connection

What it means

Error "BUG: block not specified which handles connection" thrown in fluent/fluentd.

Source

Thrown at lib/fluent/plugin_helper/server.rb:80

      #   source_addr = conn.remote_host
      #   source_port = conn.remote_port
      #   conn.data do |data|
      #     # on data
      #     conn.write resp # ...
      #     conn.close
      #   end
      # end
      def server_create_connection(title, port, proto: nil, bind: '0.0.0.0', shared: true, backlog: nil, tls_options: nil, **socket_options, &block)
        proto ||= (@transport_config && @transport_config.protocol == :tls) ? :tls : :tcp

        raise ArgumentError, "BUG: title must be a symbol" unless title && title.is_a?(Symbol)
        raise ArgumentError, "BUG: port must be an integer" unless port && port.is_a?(Integer)
        raise ArgumentError, "BUG: invalid protocol name" unless PROTOCOLS.include?(proto)
        raise ArgumentError, "BUG: cannot create connection for UDP" unless CONNECTION_PROTOCOLS.include?(proto)

        raise ArgumentError, "BUG: tls_options is available only for tls" if tls_options && proto != :tls

        raise ArgumentError, "BUG: block not specified which handles connection" unless block_given?
        raise ArgumentError, "BUG: block must have just one argument" unless block.arity == 1

        if proto == :tcp || proto == :tls
          socket_options[:linger_timeout] ||= @transport_config&.linger_timeout || 0
        end

        socket_options[:receive_buffer_size] ||= @transport_config&.receive_buffer_size

        socket_option_validate!(proto, **socket_options)
        socket_option_setter = ->(sock){ socket_option_set(sock, **socket_options) }

        case proto
        when :tcp
          server = server_create_for_tcp_connection(shared, bind, port, backlog, socket_option_setter, &block)
        when :tls
          transport_config = if tls_options
                               server_create_transport_section_object(tls_options)
                             elsif @transport_config && @transport_config.protocol == :tls

View on GitHub (pinned to dd45c6e18d)

When it happens

Trigger: Thrown at lib/fluent/plugin_helper/server.rb:80 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/4201bfe76e44826f. Report an issue: GitHub.