When I get these kind of messages it is because the internet connection
has failed. Using a laptop I find most often the WiFi switch is in the
off position. unless you have sent this message on another machine, I
would be looking for the switch. or just verify I have told the
connection manager to connect before I clicked the update manager Icon.
Other problems may be the repository server went down when you were
trying to update. If that were the case you could likely try again and
have it do it's job. I am sure in your case because of the release, the
last option would not fit (Release no longer supported).

Because I am a control freak. I don't tell the connection manager to
connect automatically. If I only used my machine at home I may turn that
option on but I don't like my machine connecting to open networks
without me knowing.