Ubuntu 10.04 is quite old, you can’t just upgrade it right away using do-release-upgrade, you should try the following steps:
sudo apt-get update sudo apt-get dist-upgrade sudo apt-get install update-manager-core sudo do-release-upgrade
If that’s still doesn’t work, replace /etc/apt/sources.list with this file
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to# newer versions of the distribution. deb http://ubuntu.datahop.net/ubuntu/ precise main restricted deb-src http://ubuntu.datahop.net/ubuntu/ precise main restricted ## Major bug fix updates produced after the final release of the ## distribution. deb http://ubuntu.datahop.net/ubuntu/ precise-updates main restricted deb-src http://ubuntu.datahop.net/ubuntu/ precise-updates main restricted ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team. Also, please note that software in universe WILL NOT receive any ## review or updates from the Ubuntu security team. deb http://ubuntu.datahop.net/ubuntu/ precise universe deb-src http://ubuntu.datahop.net/ubuntu/ precise universe deb http://ubuntu.datahop.net/ubuntu/ precise-updates universe deb-src http://ubuntu.datahop.net/ubuntu/ precise-updates universe ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team, and may not be under a free licence. Please satisfy yourself as to ## your rights to use the software. Also, please note that software in ## multiverse WILL NOT receive any review or updates from the Ubuntu ## security team. deb http://ubuntu.datahop.net/ubuntu/ precise multiverse deb-src http://ubuntu.datahop.net/ubuntu/ precise multiverse deb http://ubuntu.datahop.net/ubuntu/ precise-updates multiverse deb-src http://ubuntu.datahop.net/ubuntu/ precise-updates multiverse ## N.B. software from this repository may not have been tested as ## extensively as that contained in the main release, although it includes ## newer versions of some applications which may provide useful features. ## Also, please note that software in backports WILL NOT receive any review ## or updates from the Ubuntu security team. deb http://ubuntu.datahop.net/ubuntu/ precise-backports main restricted universe multiverse deb-src http://ubuntu.datahop.net/ubuntu/ precise-backports main restricted universe multiverse deb http://ubuntu.datahop.net/ubuntu/ precise-security main restricted deb-src http://ubuntu.datahop.net/ubuntu/ precise-security main restricted deb http://ubuntu.datahop.net/ubuntu/ precise-security universe deb-src http://ubuntu.datahop.net/ubuntu/ precise-security universe deb http://ubuntu.datahop.net/ubuntu/ precise-security multiverse deb-src http://ubuntu.datahop.net/ubuntu/ precise-security multiverse ## Uncomment the following two lines to add software from Canonical's ## 'partner' repository. ## This software is not part of Ubuntu, but is offered by Canonical and the ## respective vendors as a service to Ubuntu users. deb http://archive.canonical.com/ubuntu precise partner deb-src http://archive.canonical.com/ubuntu precise partner ## Uncomment the following two lines to add software from Ubuntu's ## 'extras' repository. ## This software is not part of Ubuntu, but is offered by third-party ## developers who want to ship their latest software. deb http://extras.ubuntu.com/ubuntu precise main deb-src http://extras.ubuntu.com/ubuntu precise main