Basically this is no different than any other upgrade of lenny you've been doing. The only difference is that you first need to make sure your package list still contains references to lenny as explained in Section A.2, “Checking your sources list”.

If you upgrade your system using a Debian mirror, it will automatically be upgraded to the latest lenny point release.

If any of the lines in your /etc/apt/sources.list refer to 'stable', you are effectively already “using” squeeze. This might not be what you want if you are not ready yet for the upgrade. If you have already run apt-get update, you can still get back without problems following the procedure below.

If you have also already installed packages from squeeze, there probably is not much point in installing packages from lenny anymore. In that case you will have to decide for yourself whether you want to continue or not. It is possible to downgrade packages, but that is not covered here.

Open the file /etc/apt/sources.list with your favorite editor (as root) and check all lines beginning with deb http: or deb ftp: for a reference to “stable”. If you find any, change stable to lenny.

If you have any lines starting with deb file:, you will have to check for yourself if the location they refer to contains an lenny or a squeeze archive.

	Important
	Do not change any lines that begin with deb cdrom:. Doing so would invalidate the line and you would have to run apt-cdrom again. Do not be alarmed if a 'cdrom' source line refers to “unstable”. Although confusing, this is normal.

If you've made any changes, save the file and execute

# apt-get update

to refresh the package list.

If your system is localised and is using a locale that is not based on UTF-8 you should strongly consider switching your system over to using UTF-8 locales. In the past, there have been bugs identified that manifest itself only when using a non-UTF-8 locale. On the desktop, such legacy locales are supported through ugly hacks in the libraries internals, and we cannot decently provide support for users who still use them.

To configure your system's locale you can run dpkg-reconfigure locales. Ensure you select an UTF-8 locale when you are presented with the question asking which locale to use as a default in the system. In addition, you should review the locale settings of your users and ensure that they do not have legacy locales definitions in their configuration environment.