W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/utopic-security/main/source/Sources 404 Not Found [IP: 80] ....


14.10 is now EOL. See this

Consider upgrading to 15.10 instead of trying to keep going after EOL.

One might suggest that non LTS releases have a ridiculously short lifetime (9 months feels short to me), but it's a tradeoff. You get the latest/greatest, but have to upgrade more often :)

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