puppetlabs/puppet · error · ArgumentError

The format must be a one letter format specifier, got '#{@fo

Error message

The format must be a one letter format specifier, got '#{@format}'

What it means

Error "The format must be a one letter format specifier, got '#{@format}'" thrown in puppetlabs/puppet.

Source

Thrown at lib/puppet/pops/types/string_converter.rb:111

    DELIMITER_MAP = {
      '[' => ['[', ']'],
      '{' => ['{', '}'],
      '(' => ['(', ')'],
      '<' => ['<', '>'],
      '|' => ['|', '|'],
      :space => ['', '']
    }.freeze

    def initialize(fmt)
      @orig_fmt = fmt
      match = FMT_PATTERN.match(fmt)
      unless match
        raise ArgumentError, "The format '#{fmt}' is not a valid format on the form '%<flags><width>.<prec><format>'"
      end

      @format = match[4]
      unless @format.is_a?(String) && @format.length == 1
        raise ArgumentError, "The format must be a one letter format specifier, got '#{@format}'"
      end

      @format = @format.to_sym
      flags  = match[1].split('') || []
      unless flags.uniq.size == flags.size
        raise ArgumentError, "The same flag can only be used once, got '#{fmt}'"
      end

      @left  = flags.include?('-')
      @alt   = flags.include?('#')
      @plus  = if flags.include?(' ')
                 :space
               else
                 flags.include?('+') ? :plus : :ignore
               end
      @zero_pad = flags.include?('0')

      @delimiters = nil

View on GitHub (pinned to e227c27540)

When it happens

Trigger: Thrown at lib/puppet/pops/types/string_converter.rb:111 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of puppetlabs/puppet@e227c27540 (2026-08-21). Data as JSON: /api/errors/bf40ee1ca83c47ce. Report an issue: GitHub.