upgrading from 12.04 to 14.04

[Don Parsons]

Hello,
When I click on "Upgrade" I get:

Unable to load page

Problem occurred while loading the URL 
http://archive.ubuntu.com/ubuntu/dists/trusty-updates/main/dist-upgrader-all/current/ReleaseAnnouncement.html?lang=en_US&os=ubuntu&ver=14.04.1%20LTS

Cannot resolve proxy hostname ()

How do I get the upgrade to work properly?
When it does, will all my present LibreOffice documents be preserved?
Tnanks
Don Parsons

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