Unable to upgrade to 13.10 from 13.04

[sk]

Update manager shows a message, Ubuntu 13.10 is available.
On selecting update option, the usual distribution upgrade dialog comes. On accepting release notes and updating the software channels, it gives an error saying unable to upgrade and report bug unless on a development/pre-release version

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: ubuntu-release-upgrader-core 1:0.192.13
ProcVersionSignature: Ubuntu 3.8.0-31.46-generic 3.8.13.8
Uname: Linux 3.8.0-31-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 2.9.2-0ubuntu8.3
Architecture: amd64
CrashDB: ubuntu
Date: Fri Oct 18 17:53:34 2013
MarkForUpload: True
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to raring on 2013-10-18 (0 days ago)
VarLogDistupgradeTermlog: