The system network services are not compatible with this version.

[Michal Jaegermann]

On Sat, May 28, 2011 at 02:14:36PM +0800, Frederic Muller wrote:
> 
> 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.

Is that really something which would bar you from configuring your
network connection by yourself using 'ip'?  I understand that you
would like NM to work but at this moment you are trying to recover
from a dead end.  Alternatively you can boot "rescue" from your
installation media, which presumably will bring up a network
connection, and adjust installed packages from there.

   Michal