Comment 2 for bug 752201

It is 'sudo apt-get update' to update APTs knowledge about packages and 'sudo apt-get install whatever' there 'whatever' is the name of a package. You can't execute both commands at the same time and a package with the name 'update' doesn't exist as the error message tells you.

You should report that bug against your 'update manager' as i don't know what you are talking about then you say something about GUI (i would reassign it, but i don't know what you mean…)