In RC2 some critical bugs existed.. You can fix these bugs as shown below:
Preparation
Firstly we need to prepare ourselves for the update. This will pull in the new
kernel package too with extra WiFi and NFS support.
sudo apt-get update && sudo apt-get upgrade
Missing Loopback Interface
This affects most networking services, including the Firewall. Please open the /etc/network/interfaces file as the superuser:
gksudo gedit /etc/network/interfaces
You need to append these lines to the end of file and save
# The loopback network interface
auto lo
iface lo inet loopback
Missing Printer Drivers
The cups-driver-gutenprint package wasn’t installed by default. Rectify by issuing the following command
sudo apt-get install cups-driver-gutenprint