ruby/rubygems · error · TypeError

invalid Gem::Specification format #{array.inspect}

Error message

invalid Gem::Specification format #{array.inspect}

What it means

Error "invalid Gem::Specification format #{array.inspect}" thrown in ruby/rubygems.

Source

Thrown at lib/rubygems/specification.rb:1322

    ensure
      Object.__send__(:remove_const, "YAML") if yaml_set
    end

    spec = Gem::Specification.new
    spec.instance_variable_set :@specification_version, array[1]

    current_version = CURRENT_SPECIFICATION_VERSION

    field_count = if spec.specification_version > current_version
      spec.instance_variable_set :@specification_version,
                                 current_version
      MARSHAL_FIELDS[current_version]
    else
      MARSHAL_FIELDS[spec.specification_version]
    end

    if array.size < field_count
      raise TypeError, "invalid Gem::Specification format #{array.inspect}"
    end

    spec.instance_variable_set :@rubygems_version,          array[0]
    # spec version
    spec.instance_variable_set :@name,                      array[2]
    spec.instance_variable_set :@version,                   array[3]
    spec.date =                                             array[4]
    spec.instance_variable_set :@summary,                   array[5]
    spec.instance_variable_set :@required_ruby_version,     array[6]
    spec.instance_variable_set :@required_rubygems_version, array[7]
    spec.platform =                                         array[8]
    spec.instance_variable_set :@dependencies,              array[9]
    # offset due to rubyforge_project removal
    spec.instance_variable_set :@email,                     array[11]
    spec.instance_variable_set :@authors,                   array[12]
    spec.instance_variable_set :@description,               array[13]
    spec.instance_variable_set :@homepage,                  array[14]
    # offset due to has_rdoc removal

View on GitHub (pinned to 86cbb817a3)

Solutions

1. The marshaled specification array is invalid; rebuild the gem with a compatible RubyGems version

When it happens

Trigger: Thrown at lib/rubygems/specification.rb:1322 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of ruby/rubygems@86cbb817a3 (2026-08-23). Data as JSON: /api/errors/b56a9f121d7e5443. Report an issue: GitHub.