title: Active Admin won't install: superclass mismatch for class StringIO (TypeError)
body: <p>I was recently trying to install Active Admin but it keeps producing this error below. I have added activeadmin, devise, draper, cancancan, and pundit to the gemfile. For reference, I am trying to install Active Admin on a basic blog app for ruby on rails (<a href="https://guides.rubyonrails.org/getting_started.html" rel="nofollow noreferrer">https://guides.rubyonrails.org/getting_started.html</a>)</p>
  <p>Command:</p>
  <p><code>rails g active_admin:install</code></p>
  <p>Error:</p>
  <pre><code>/home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require': superclass mismatch for class StringIO (TypeError)
  from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
      from /home/hjamal/.rvm/rubies/ruby-2.5.8/lib/ruby/2.5.0/psych/nodes/node.rb:2:in `&lt;top (required)&gt;'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
      from /home/hjamal/.rvm/rubies/ruby-2.5.8/lib/ruby/2.5.0/psych/nodes.rb:2:in `&lt;top (required)&gt;'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
      from /home/hjamal/.rvm/rubies/ruby-2.5.8/lib/ruby/2.5.0/psych.rb:14:in `&lt;top (required)&gt;'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
      from /home/hjamal/.rvm/rubies/ruby-2.5.8/lib/ruby/2.5.0/yaml.rb:6:in `&lt;top (required)&gt;'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/compile_cache/yaml.rb:55:in `init!'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/compile_cache/yaml.rb:50:in `install!'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/compile_cache.rb:20:in `setup'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap.rb:70:in `setup'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap.rb:112:in `default_setup'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/bootsnap-1.9.1/lib/bootsnap/setup.rb:4:in `&lt;top (required)&gt;'
      from /home/hjamal/blog/config/boot.rb:4:in `require'
      from /home/hjamal/blog/config/boot.rb:4:in `&lt;top (required)&gt;'
      from /home/hjamal/blog/config/application.rb:1:in `require_relative'
      from /home/hjamal/blog/config/application.rb:1:in `&lt;top (required)&gt;'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/spring-3.0.0/lib/spring/application.rb:92:in `require'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/spring-3.0.0/lib/spring/application.rb:92:in `preload'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/spring-3.0.0/lib/spring/application.rb:155:in `serve'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/spring-3.0.0/lib/spring/application.rb:143:in `block in run'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/spring-3.0.0/lib/spring/application.rb:137:in `loop'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/spring-3.0.0/lib/spring/application.rb:137:in `run'
      from /home/hjamal/.rvm/gems/ruby-2.5.8/gems/spring-3.0.0/lib/spring/application/boot.rb:19:in `&lt;top (required)&gt;'
      from /home/hjamal/.rvm/rubies/ruby-2.5.8/lib/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:85:in `require'
      from /home/hjamal/.rvm/rubies/ruby-2.5.8/lib/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:85:in `require'
      from -e:1:in `&lt;main&gt;'
  
  
  
   
  </code></pre>