Failed to upgrade ubuntu 12.10 to 13.04 beacause package size mismatch

I was upgrading my ubuntu 12.10 to 13.04, using following command:

sudo do-release-upgrade

everything is OK until I get following error message :

 Could not download the upgrades
The upgrade has aborted. Please check your Internet connection or
installation media and try again. All files downloaded so far have
been kept.
Failed to fetch
Size mismatch
Failed to fetch
Size mismatch
Restoring original system state
Aborting
Reading package lists... Done
Building dependency tree
Reading state information... Done
Building data structures... Done

what should I do for this?

1 Answer

Have you tried doing it via the GUI it may be easier?

Make sure you backup, it may cause you some frustration later on if not.

Start off with do-release-upgrade -c

if this fails You may need to install the update-manager-core package if your distro is no longer supported.