I want to upgrade from Ubuntu 10.10 to 11.04. When I start upgrading, a window appeared with the following message:
authentication failed there may be a problem with the network or with a server
Please guide me on how can I resolve this problem.
Try this(not best way to solve this problem but it is working):
Download Ubuntu 11.04 and make LiveCD on pendrive or cd/dvd.
Use "upgrade Ubuntu" in options.