Thank you Colin. I appear to have fixed the problem by editing the /etc/apt/sources.list by replacing all occurrences of 'http://ports.ubuntu.com/ubuntu-ports/' with 'http://archive.ubuntu.com/ubuntu/'
After saving the file the Update Manager showed approx. 40 new updates that were not in the list a few seconds prior. -- Power PC Security Repositories Bug https://bugs.launchpad.net/bugs/213112 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs