Could you try running synaptic from terminal using "sudo synaptic" and click the repositories menuitem to see whether it logs any error why it could not start software sources?
** Changed in: software-properties (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/902431 Title: in synaptic setting->repositories fails to open its dialog if software-properties-gtk is installed To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/software-properties/+bug/902431/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs