ruby/rubygems · error · RuntimeError

Unable to determine name from existing gemspec. Use :name =>

Error message

Unable to determine name from existing gemspec. Use :name => 'gemname' in #install_tasks to manually set it.

What it means

Error "Unable to determine name from existing gemspec. Use :name => 'gemname' in #install_tasks to manually set it." thrown in ruby/rubygems.

Source

Thrown at lib/bundler/gem_helper.rb:36

      def tag_prefix=(prefix)
        instance.tag_prefix = prefix
      end

      def gemspec(&block)
        gemspec = instance.gemspec
        block&.call(gemspec)
        gemspec
      end
    end

    attr_reader :spec_path, :base, :gemspec

    attr_writer :tag_prefix

    def initialize(base = nil, name = nil)
      @base = File.expand_path(base || SharedHelpers.pwd)
      gemspecs = name ? [File.join(@base, "#{name}.gemspec")] : Gem::Util.glob_files_in_dir("{,*}.gemspec", @base)
      raise "Unable to determine name from existing gemspec. Use :name => 'gemname' in #install_tasks to manually set it." unless gemspecs.size == 1
      @spec_path = gemspecs.first
      @gemspec = Bundler.load_gemspec(@spec_path)
      @tag_prefix = ""
    end

    def install
      built_gem_path = nil

      desc "Build #{name}-#{version}.gem into the pkg directory."
      task "build" do
        built_gem_path = build_gem
      end

      desc "Generate SHA512 checksum of #{name}-#{version}.gem into the checksums directory."
      task "build:checksum" => "build" do
        build_checksum(built_gem_path)
      end

View on GitHub (pinned to 86cbb817a3)

Solutions

1. Add :name => 'gemname' to the install_tasks call in your Rakefile
2. Or ensure a single valid gemspec exists so the name can be inferred

When it happens

Trigger: Thrown at lib/bundler/gem_helper.rb:36 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/09742b5c28e7f565. Report an issue: GitHub.