Comment 2 for bug 247718

I encountered a similar problem with trying to upgrade fontconfig-config (Hardy-proposed -> Intrepid alpha 1)

In the terminal I used to launch update-manager (with gksu) is the following:
alex@alex-laptop:~$ gksu "update-manager -d"
Fontconfig warning: "/etc/fonts/conf.d/53-monospace-lcd-filter.conf", line 17: invalid constant used : lcdfilterlegacy
Fontconfig warning: "/etc/fonts/conf.d/53-monospace-lcd-filter.conf", line 17: invalid constant used : lcdfilterlegacy
Fontconfig warning: "/etc/fonts/conf.d/53-monospace-lcd-filter.conf", line 17: invalid constant used : lcdfilterlegacy
Fontconfig warning: "/etc/fonts/conf.d/53-monospace-lcd-filter.conf", line 17: invalid constant used : lcdfilterlegacy

Several apport dialogs came up, for fontconfig as well as others such as update-manager. Each of them went through the data-collection and upload steps, but no Firefox window opened. Eventually update-manager crashed with a rather serious warning. Something along the lines of "The upgrade failed, and ends now. Your system may be broken. Run dpkg --configure -a."

I'm currently running dpkg --configure -a, which is apparently making some progress with installing further, but still having problems.