To upgrade to Plone 2.5, I needed to upgrade broach to ubuntu dapper. I was a bit concerned that our main production server would be at risk of this upgrade, but it only required the execution of three commands and a wait of 20 minutes, and voila!

First, change all occurences of “breezy” to “dapper” in /etc/apt/sources.list

apt-get update

apt-get dist-upgrade

(20 minutes of waiting)

Now I could install Zope 2.9, which was only available in Dapper. All ubuntu users wanting to use Plone 2.5, switch to dapper!