Ruby on Rails error: superclass mismatch for class StringIO (TypeError)

Question

I am getting an error while creating a ruby on rails project. In command, I created a new project by typing rails new club, then bundle. Now, when I try to create my models and controllers by typing and entering rails g resource Club name, I get this error: superclass mismatch for class StringIO (TypeError).

gems/bootsnap-1.9.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:
in `require': superclass mismatch for class StringIO (TypeError)

I don't even has a class named StringIO, so I'm not sure where it came from.

• ruby version: 2.6.8
• rails: 6.1.4.1

Answer 1

Try reverting to an earlier version of StringIO

gem install stringio -v 0.1.4

gem uninstall stringio # remove 3.0.0 and 3.0.1

Answer 2

As others have said on @jason-lee answer, for many people, this can be fixed just by uninstalling the existing stringio then running bundle install again.

    gem uninstall stringio
    bundle