The system network services are not compatible with this version.

[Frederic Muller]

I'm having this bug https://bugzilla.redhat.com/show_bug.cgi?id=696278 
which is not a duplicate of 
https://bugzilla.redhat.com/show_bug.cgi?id=678553 :

It just happened with the latest pushed update of NetworkManager (I 
updated this morning) on a clean F15 system (not an upgraded one). 
Service is started (as opposed to cited bug above) and I have tried to 
downgrade the 3 packages that were upgraded but since there is no 
connectivity I can't.

Any hint welcome.

Thanks a lot.

Fred