Upgrading to Redmine 3.0.1 on Debian Wheezy

Today I wanted to upgrade my Redmine installation from Redmine 2.6.x to the new version Redmine 3.0.1. Since I already have processed many Redmine updates I thought this update would be easy as always, but certainly I ran into an unexpected problem. After I followed all steps from the upgrade manual I restarted the apache2 process, so mod_passenger reloads the Redmine application. After that, Redmine did'nt start and showed the following error message:

undefined method `page_cache_directory' for ActionController::Base:Class

After doing some Google search, I found this article on stackoverflow, which pointed me to the right direction. Actually, Debian Wheezy comes with an pretty old version of Phusion Passenger (3.0.x), so I performed the following steps and installed a newer version (4.0.x) of Phusion Passenger from Wheezy Backports.

First I added Wheezy Backports to my apt sources file /etc/apt/sources.list

deb http://http.debian.net/debian wheezy-backports main

Next I used apt-get update to update the local apt repositories and finally I installed Phusion Passenger from the Wheezy Backports with the following command

apt-get -t wheezy-backports install "libapache2-mod-passenger"

After this, I restarted the apache2 process and Redmine 3.0.1 started successfully.