ruby/rubygems · error · ArgumentError

Malformed version number string #{version}

Error message

Malformed version number string #{version}

What it means

Error "Malformed version number string #{version}" thrown in ruby/rubygems.

Source

Thrown at lib/rubygems/version.rb:228

  end

  @@all = {}
  @@bump = {}
  @@release = {}

  def self.new(version) # :nodoc:
    return super unless self == Gem::Version

    @@all[version] ||= super
  end

  ##
  # Constructs a Version from the +version+ string.  A version string is a
  # series of digits or ASCII letters separated by dots.

  def initialize(version)
    unless self.class.correct?(version)
      raise ArgumentError, "Malformed version number string #{version}"
    end

    # If version is an empty string convert it to 0
    version = 0 if version.nil? || (version.is_a?(String) && /\A\s*\Z/.match?(version))

    @version = version.to_s

    # optimization to avoid allocation when given an integer, since we know
    # it's to_s won't have any spaces or dashes
    unless version.is_a?(Integer)
      @version = @version.strip
      @version.gsub!("-",".pre.")
    end
    @version = -@version
    @segments = nil
    @sort_key = compute_sort_key
  end

View on GitHub (pinned to 86cbb817a3)

Solutions

1. Use a valid version string: digits separated by dots (e.g. '1.2.3'), optionally with a letter prerelease segment

When it happens

Trigger: Thrown at lib/rubygems/version.rb:228 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 ruby/rubygems@86cbb817a3 (2026-08-23). Data as JSON: /api/errors/d3901d2b7010dd91. Report an issue: GitHub.