Currently, when I run the Update Manager in 12.04.1 LTS , I get since some weels:
How can I update from this state?
Update
$ sudo apt-get update Get:1 http://at.archive.ubuntu.com precise Release.gpg [198 B] ... Hit http://at.archive.ubuntu.com precise-backports/universe Translation-en Fetched 198 B in 1s (146 B/s) Reading package lists... Done W: GPG error: http://at.archive.ubuntu.com precise Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key
/etc/apt/sources.list
file. Also, try runningsudo apt-get update
and then run the Update manager again.