bcrypt LoadError: Cannot load such file

make sure you not only run bundle install, but that you ALSO kill the server and reload it to make sure it then loads in the new gems. you can also check your gemfile for 'spring'. if thats loaded too, you'll want to comment that out, reload the server and try it then. that should take care of all possibilities.

After running bundle install to install bcrypt, just restart the rails server.
That should help your application to reload and pick up the newly installed bcrypt dependency.