Comment 4 for bug 780678

I was hit by this bug as well during the upgrade to Natty - was pretty scary to see the entire upgrade process fail because of this, but fortunately it looks like nothing else was affected and the upgrade otherwise went ok (I hope).

I just wanted to share a simpler workaround I found, which may help find the culprit as well:

before running the upgrade (or "apt-get install -f" if it's too late and it already broke), just move the files under /usr/lib/mozilla/plugins/ to somewhere else (or rename the plugins folder and create an empty one in its place), and after installation/fixing is complete, move them back in place.

FWIW, I played around with this and found that the plugin to blame in my case was skypebuttons.so - moving it alone was enough to prevent the failure. I don't know if this is the same one causing trouble for others too. In fact I have no idea what it is - it seems to be a Kopete plugin (not anything from Skype itself), and I don't even use Kopete...

Anyway, I hope this helps someone.