ruby/rubygems · error · Gem::SafeMarshal::Reader::NotImplementedError

Reading Marshal objects of type struct is not implemented

Error message

Reading Marshal objects of type struct is not implemented

What it means

Error "Reading Marshal objects of type struct is not implemented" thrown in ruby/rubygems.

Source

Thrown at lib/rubygems/safe_marshal/reader.rb:294

      def read_module
        raise NotImplementedError, "Reading Marshal objects of type module is not implemented"
      end

      def read_class_or_module
        raise NotImplementedError, "Reading Marshal objects of type class_or_module is not implemented"
      end

      def read_data
        raise NotImplementedError, "Reading Marshal objects of type data is not implemented"
      end

      def read_regexp
        raise NotImplementedError, "Reading Marshal objects of type regexp is not implemented"
      end

      def read_struct
        raise NotImplementedError, "Reading Marshal objects of type struct is not implemented"
      end

      def read_user_class
        name = read_element
        wrapped_object = read_element
        Elements::UserClass.new(name, wrapped_object)
      end
    end
  end
end

View on GitHub (pinned to 86cbb817a3)

Solutions

1. The gem metadata uses a Marshal construct RubyGems does not support; rebuild the gem with a current RubyGems

When it happens

Trigger: Thrown at lib/rubygems/safe_marshal/reader.rb:294 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/79be535920489ef6. Report an issue: GitHub.