deivid-rodriguez/byebug · error · Byebug::Printers::Base::MissedArgument

Missed argument #{key} for '#{string}'

Error message

Missed argument #{key} for '#{string}'

What it means

Error "Missed argument #{key} for '#{string}'" thrown in deivid-rodriguez/byebug.

Source

Thrown at lib/byebug/printers/base.rb:39

      def locate(path)
        result = nil
        contents.each_value do |contents|
          result = parts(path).reduce(contents) do |r, part|
            r&.key?(part) ? r[part] : nil
          end
          break if result
        end
        raise MissedPath, "Can't find part path '#{path}'" unless result

        result
      end

      def translate(string, args = {})
        # they may contain #{} string interpolation
        string.gsub(/\|\w+$/, "").gsub(/([^#]?){([^}]*)}/) do
          key = Regexp.last_match[2].to_s
          raise MissedArgument, "Missed argument #{key} for '#{string}'" unless args.key?(key.to_sym)

          "#{Regexp.last_match[1]}#{args[key.to_sym]}"
        end
      end

      def parts(path)
        path.split(SEPARATOR)
      end

      def contents
        @contents ||= contents_files.each_with_object({}) do |filename, hash|
          hash[filename] = YAML.load_file(filename) || {}
        end
      end

      def array_of_args(collection, &_block)
        collection_with_index = collection.each.with_index
        collection_with_index.each_with_object([]) do |(item, index), array|

View on GitHub (pinned to 25476b18d9)

Solutions

1. Pass every {placeholder} used in the template string as a symbol key in the args hash to translate/print.
2. Fix the template to remove or rename placeholders that have no matching argument.

Example fix

translate('Line {line}', { line: 5 })   # provide :line so {line} can be substituted

When it happens

Trigger: Thrown at lib/byebug/printers/base.rb:39 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of deivid-rodriguez/byebug@25476b18d9 (2026-08-23). Data as JSON: /api/errors/037a318ab2ad06c7. Report an issue: GitHub.