Perl conflicts during upgrade to squeeze/testing

Question

In a pursuit to get python2.7 on my server system (running Debian squeeze), I've run into some trouble upgrading all packages. I'm completely at a loss of what to do from here:

# apt-get upgrade -f
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Correcting dependencies... failed.
The following packages have unmet dependencies:
 libalgorithm-diff-xs-perl : Depends: perlapi-5.10.1
 libapt-pkg-perl : Depends: perlapi-5.10.1
 libauthen-pam-perl : Depends: perlapi-5.10.0
 libcurses-perl : Depends: perlapi-5.10.1
 libdbd-mysql-perl : Depends: perlapi-5.10.1
 libdbi-perl : Depends: perlapi-5.10.1
 libfont-freetype-perl : Depends: perlapi-5.10.0
 libgd-gd2-noxpm-perl : Depends: perlapi-5.10.1
 libhtml-parser-perl : Depends: perlapi-5.10.1
 libio-pty-perl : Depends: perlapi-5.10.1
 liblchown-perl : Depends: perlapi-5.10.1
 liblocale-gettext-perl : PreDepends: perlapi-5.10.0
 libnet-ssleay-perl : Depends: perlapi-5.10.1
 libterm-readkey-perl : Depends: perlapi-5.10.0
 libtext-charwidth-perl : Depends: perlapi-5.10.0
 libtext-iconv-perl : Depends: perlapi-5.10.0
 libuuid-perl : Depends: perlapi-5.10.1
 perl-base : Conflicts: defoma (< 0.11.12) but 0.11.11 is installed
 perl-modules : Recommends: libarchive-extract-perl but it is not installed
                Recommends: libmodule-pluggable-perl
                Recommends: libpod-latex-perl but it is not installed
                Recommends: libterm-ui-perl but it is not installed
                Recommends: libtext-soundex-perl but it is not installed
                Recommends: libcgi-pm-perl
                Recommends: libmodule-build-perl
                Recommends: libpackage-constants-perl but it is not installed
                Conflicts: defoma (< 0.11.12) but 0.11.11 is installed
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.
E: Unable to correct dependencies

In my sources.list I have:

deb http://ftp.dk.debian.org/debian/ squeeze main non-free
deb-src http://ftp.dk.debian.org/debian/ squeeze main

deb http://security.debian.org/ squeeze/updates main
deb-src http://security.debian.org/ squeeze/updates main

# squeeze-updates, previously known as 'volatile'
deb http://ftp.dk.debian.org/debian/ squeeze-updates main
deb-src http://ftp.dk.debian.org/debian/ squeeze-updates main

deb http://mirrors.dotsrc.org/cran/bin/linux/debian squeeze-cran/
deb http://nginx.org/packages/debian/ squeeze nginx

deb-src http://http.debian.net/debian/ sid main contrib non-free

deb http://ftp.dk.debian.org/debian/ testing main contrib non-free

Any suggestions on how to proceed?

Answer 1

The system needs your help to proceed, use aptitude instead of apt-get.

aptitude full-upgrade

You'll get the same info and a possible solution which will involve updating some packages and removing others. If the situation is acceptable, proceed. Else, let's say aptitude suggests the removal of gnome and that's not acceptable for you. Next to gnome, in the list of packages to upgrade, remove, etc you'll see a number, for example 23 gnome. Type R23 to discard all the solutions that involve removing gnome. Tap Intro and then n, to not accept the solution.

Aptitude will present you another temptative solution, which won't suggest the removal of gnome (if available). Rinse and repeat until an acceptable solution arises.

This is just a starting point, remember, man aptitude is your best friend.