After a security update on a ubuntu 12.04 server redmine 2.5 is broken (error 500). we recoginized that libapache2-mod-passenger was updated from
libapache2-mod-passenger=2.2.11debian-2
to
libapache2-mod-passenger=2.2.11debian-2+deb6u1ubuntu12.04.1
Downgrading this package again solved the problem. What can I do to not run into same problem with next security update?