`': superclass mismatch for class Server (TypeError)

Question

I have seen this and several others question, but their problems are not similar to mine.

I have added the following code to the config/boot.rb , to run

Answer 1

For Rails 5.1 the following line in config/boot.rb will do the trick:

ENV['PORT'] = '8081'

Link to the source.

Answer 2

A better way to do what you want:

require 'rails/commands/server'

module DefaultOptions
  def default_options
    super.merge!(Port: 8081)
  end
end

Rails::Server.prepend(DefaultOptions)

The reason for the error message is because you are attempting to redefine the Rails::Server class and changing it's inheritance structure. Rails::Server inherits from ::Rack::Server, however your code is trying to say it no longer does. Therefore, you get your superclass mismatch error.

Answer 3

In Rails 5.2

in config/puma.rb I added this code.

#port        ENV.fetch("PORT") { 3000 }
bind        'tcp://0.0.0.0:3001'

And it works!