Comment 47 for bug 249340

Thank you all for all the information. I manage to workaround this problem.
After the installation failed due to the "locale" issue, I restarted my system, selected the latest installed kernel, tried Ctrl+Alt+F1 (which showed me the boot process in console mode but in the end I was still under Gnome logged in), and then I just opened a terminal under Gnome and perform the apt-get dist-upgrade and the dpkg-reconfigure -a.
It was painfully slow, but in the end worth it, as my system seems to be working properly.