Ruby 2.4 and Rails 4 stack level too deep (SystemStackError)

Question

I\'m trying to run newly created project in Rails 4.0.8 but I receive and error:

    rails s
=> Booting WEBrick
=> Rails 4.0.8 application starting in         


        

Answer 1

In regards to the error, you're running the just-released Ruby 2.4, which Rails and ActiveSupport (especially older versions of these) most likely don't support yet.

This Rails guide states your Rails version (4.0.8) prefers Ruby 2.0.

You can fix the error by either upgrading your Rails installation (gem 'rails', '5.0') or downgrading to an older version of Ruby with a version manager (e.g. $ rvm install 2.3.0; rvm use 2.3.0).