fluent/fluentd · error · Fluent::ConfigError

Argument in <storage ARG> uses invalid characters: '#{usage}

Error message

Argument in <storage ARG> uses invalid characters: '#{usage}'

What it means

Error "Argument in <storage ARG> uses invalid characters: '#{usage}'" thrown in fluent/fluentd.

Source

Thrown at lib/fluent/plugin_helper/storage.rb:37

require 'fluent/plugin'
require 'fluent/plugin/storage'
require 'fluent/plugin_helper/timer'
require 'fluent/config/element'
require 'fluent/configurable'

module Fluent
  module PluginHelper
    module Storage
      include Fluent::PluginHelper::Timer

      StorageState = Struct.new(:storage, :running)

      def storage_create(usage: '', type: nil, conf: nil, default_type: nil)
        if conf && conf.respond_to?(:arg) && !conf.arg.empty?
          usage = conf.arg
        end
        if !usage.empty? && usage !~ /^[a-zA-Z][-_.a-zA-Z0-9]*$/
          raise Fluent::ConfigError, "Argument in <storage ARG> uses invalid characters: '#{usage}'"
        end

        s = @_storages[usage]
        if s&.running
          return s.storage
        elsif s
          # storage is already created, but not loaded / started
        else # !s
          type = if type
                   type
                 elsif conf && conf.respond_to?(:[])
                   raise Fluent::ConfigError, "@type is required in <storage>" unless conf['@type']
                   conf['@type']
                 elsif default_type
                   default_type
                 else
                   raise ArgumentError, "BUG: both type and conf are not specified"
                 end

View on GitHub (pinned to dd45c6e18d)

When it happens

Trigger: Thrown at lib/fluent/plugin_helper/storage.rb:37 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

AI-assisted analysis of fluent/fluentd@dd45c6e18d (2026-08-21). Data as JSON: /api/errors/64b5688a693c7b09. Report an issue: GitHub.