fluent/fluentd · error · Fluent::ConfigError

'add_tag_prefix' parameter must not be empty

Error message

'add_tag_prefix' parameter must not be empty

What it means

Error "'add_tag_prefix' parameter must not be empty" thrown in fluent/fluentd.

Source

Thrown at lib/fluent/plugin/in_http.rb:128

      @default_keep_time_key = nil
      @float_time_parser = nil

      # <parse> configured parser
      @custom_parser = nil
    end

    def configure(conf)
      compat_parameters_convert(conf, :parser)

      super

      if @cors_allow_credentials
        if @cors_allow_origins.nil? || @cors_allow_origins.include?('*')
          raise Fluent::ConfigError, "Cannot enable cors_allow_credentials without specific origins"
        end
      end

      raise Fluent::ConfigError, "'add_tag_prefix' parameter must not be empty" if @add_tag_prefix && @add_tag_prefix.empty?

      m = if @parser_configs.first['@type'] == 'in_http'
            @parser_msgpack = parser_create(usage: 'parser_in_http_msgpack', type: 'msgpack')
            @parser_msgpack.time_key = nil
            @parser_msgpack.estimate_current_event = false
            @parser_json = parser_create(usage: 'parser_in_http_json', type: 'json')
            @parser_json.time_key = nil
            @parser_json.estimate_current_event = false

            default_parser = parser_create(usage: '')
            @format_name = 'default'
            @parser_time_key = default_parser.time_key
            @default_time_parser = default_parser.get_time_parser
            @default_keep_time_key = default_parser.keep_time_key
            method(:parse_params_default)
          else
            @custom_parser = parser_create
            @format_name = @parser_configs.first['@type']

View on GitHub (pinned to dd45c6e18d)

When it happens

Trigger: Thrown at lib/fluent/plugin/in_http.rb:128 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/95bc048c1ef0bcf8. Report an issue: GitHub.