This question already has an answer here:

i was upgrading to 15.10 with these two commands that i found on ubuntu forums:

sudo sed -i 's/vivid/wily/g' /etc/apt/sources.list

sudo apt-get update && sudo apt-get dist-upgrade

but at some point it showed network failure and it stopped so i tried this command:

apt-get update

but the problem i encountered is that even on rebooting on screen it flashes 15.04 now if i redo the upper two commands will it create duplicate repositories that i will have to take care of? because i dont have enough space on my laptop to waste. and any other detail for my upgrade to 15.10 would be highly appreciated!

marked as duplicate by xangua, karel, Fabby, Eric Carvalho, Seth Jul 27 '15 at 23:54

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • Not only you do the wrong thing by replacing the release name in the repository list to upgrade but also Willy is the current development Ubuntu release and as such it is not (yet) supported in Askubuntu. – xangua Jul 27 '15 at 16:41
  • 1
    Clearly you did sudo some_command_I_do_not_understand. This is ALWAYS unwise. The sed command changes all occurrances of the string "vivid" to the string "willy" in the file /etc/apt/sources.list. If it worked the first time, it will have nothing to do the second time. – waltinator Jul 27 '15 at 16:45
  • Do sudo sed -i 's/wily/vivid/g' /etc/apt/sources.list and then run update. Then start over – ps95 Jul 27 '15 at 17:04
  • @waltinator you are pretty close but at that time i rechecked that post was made by some person with high reputation at forum. i am just a beginner and i will keep your advice in mind. – dinesh agarwal Jul 27 '15 at 17:50
  • i dont know why the question has been marked duplicate as it was very specific problem that i faced . nevertheless thnx for the support! – dinesh agarwal Jul 28 '15 at 6:14

Please be aware that 15.10 is still in development. Development releases are unstable, and not suited for people who do not want to fix/report/triage bugs. If you want a stable Ubuntu version, stick to the official released versions. For added stability, choose a Ubuntu LTS release.

That said, to upgrade to a development release open your terminal by pressing Alt + F2 and type update-manager -d.

enter image description here

You can choose to upgrade from this window.

Or, If you prefer to do this from the command-line,

sudo do-release-upgrade -d

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