Debian and Ubuntu apt requirements are in the middle of a significant update. If you’re running Ubuntu MATE 16.04 you may need to take action!
apt in Debian Unstable and Ubuntu 16.04 now requires that repositories be signed with RSA keys using SHA256 or higher. Some 3rd party repositories don’t meet these requirements.
Currently the Google Music Manager, Google Talk Plugin, and SpiderOakONE repositories are affected and will cause graphical package and update managers to fail out right. So subscribe to Welcomes updates to ensure the applications above are no longer listed. Also it is recommended that if you’ve installed Google Music Manager, Google Talk Plugin or SpiderOakONE you uninstall them using Ubuntu MATE Welcome or disable their repositories in Software and Updates.
I spent last evening working with the Debian team to determine the extent of the issue and which 3rd party repositories are affected and what they need to do to become compliant. Thankfully the Google Chrome repository was updated yesterday. We’ll be contacting affected maintainers of the non-compliant repositories over the weekend.
Google Music Manager, Google Talk Plugin and SpiderOakONE are the only 3rd party repositories used by Ubuntu MATE Welcome that are not compliant with the new apt security requirements.