What is "downgrading a system" ?

In Debian world, it means to move to an older distribution (typically, to move from [:DebianUnstable:unstable] to [:DebianTesting:testing]). do not expect to get anything stable by downgrading !

Is it supported ?

So, what's the supported way ?

  1. Make a backup of your system before you upgrade. If anything is wrong, restore your backup !
  2. or Re-install.

How to downgrade a system ?

Be warned : you will be alone ! However, Auke Jilderda had documented it's experience, back in 2002 : [http://people.debian.org/~osamu/pub/downgrade.html] (plus some comments from Osamu Aoki)