Passenger: cannot load such file rubygems/builder

Question

I was trying to install passenger with Apache2 and ruby 2.0, and I had this line of error when I am doing:

passenger-install-apache2-module

Er

Answer 1

There's seems to be problems with Ruby 2.0 and passenger as pointed on this reported issue:Passenger Ruby 2.0 issue

One of the proposed solutions (can be found on one of the comments there):

git clone https://github.com/FooBarWidget/passenger.git
cd passenger
gem build passenger.gemspec
gem install passenger-3.9.5.rc3.gem (or type your actual built gem name)

Edit:

To simplify the process a pre-release version (pointing to whatever latest RC version) can also be installed in the following fashion:

gem install passenger --pre

Answer 2

Updated instructions:

$ gem install passenger --version 4.0.0.rc6
$ passenger-install-apache2-module