fluent/fluentd · error · ConfigError

'<#{subproxy.name}>' section cannot be written twice or more

Error message

'<#{subproxy.name}>' section cannot be written twice or more

What it means

Error "'<#{subproxy.name}>' section cannot be written twice or more" thrown in fluent/fluentd.

Source

Thrown at lib/fluent/config/section.rb:243

            end
            elements << Fluent::Config::Element.new(subproxy.name.to_s, '', {}, [])
          end

          # set subproxy for secret option
          elements.each { |element|
            element.corresponding_proxies << subproxy
          }

          if subproxy.required? && elements.size < 1
            logger.error "config error in:\n#{conf}" if logger
            raise ConfigError, "'<#{subproxy.name}>' sections are required" + section_stack
          end
          if subproxy.multi?
            section_params[varname] = elements.map{ |e| generate(subproxy, e, logger, plugin_class, stack + [subproxy.name], strict_config_value) }
          else
            if elements.size > 1
              logger.error "config error in:\n#{conf}" if logger
              raise ConfigError, "'<#{subproxy.name}>' section cannot be written twice or more" + section_stack
            end
            section_params[varname] = generate(subproxy, elements.first, logger, plugin_class, stack + [subproxy.name], strict_config_value)
          end
        end

        Section.new(section_params, conf)
      end

      def self.check_unused_section(proxy, conf, plugin_class)
        elems = conf.respond_to?(:elements) ? conf.elements : []
        elems.each { |e|
          next if plugin_class.nil? && Fluent::Config::V1Parser::ELEM_SYMBOLS.include?(e.name) # skip pre-defined non-plugin elements because it doesn't have proxy section
          next if e.unused_in&.empty? # the section is used at least once

          if proxy.sections.any? { |name, subproxy| e.name == subproxy.name.to_s || e.name == subproxy.alias.to_s }
            e.unused_in = []
          else
            parent_name = if conf.arg.empty?

View on GitHub (pinned to dd45c6e18d)

When it happens

Trigger: Thrown at lib/fluent/config/section.rb:243 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/5c32b2577261582f. Report an issue: GitHub.