this issue seems to be common with the 16.04 version after the latest update.
The solution as of now is to wait until Ubuntu has a fix for it.
It is the same problem and I suggested him to do an upgrade, I would suggest you to do so only if all the packages support the latest version.
Try contacting Ubuntu for the issue. Else, I would suggest to do an upgrade (not recommended if packages unsupported may break your applications) as it's a faster solution because usually the fix takes time.
P.S: In case it annoys you while working, I am attaching the solution if you need to do an upgrade.
Try using the terminal and do
sudo update-manager / go to Software & Updates and enable notify for any new version!
And do this:
sudo apt update && sudo apt dist-upgrade
To directly do the upgrade then:
sudo apt install update-manager-core
In case you were wondering if you could downgrade the update, then check here as he explains why downgrade is not recommended.
Also, there's also a way that you could clean install the older version of Ubuntu(although, why would you do that as some of your app data might be lost).