I'm currently using ubuntu 10.10 and I can not upgrade ubuntu 11.04 on my dell inspiron N5040.An error report comes up stating " Authenticating the upgrade failed. There may be a problem with the network or with the server. "
closed as too localized by Eliah Kagan, fossfreedom♦ Dec 29 '12 at 7:21
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Well not an expert here, but 10.10 is at it's End OF Life(EOL) and i'm not sure if canonical supports upgrading from a unsupported version. I hope this link helps https://help.ubuntu.com/community/NattyUpgrades
I would try the Upgrading Using the Alternate CD/DVD method on that page.
Download a live CD and boot from it. It will give you the option to upgrade previous ubuntu install. This way you can directly upgrade to 12.04 (which will be final in a week).