"Unable to download updates: The following packages have unmet dependencies:"

[cybercow]

Just for clearance sake: apt-get or just apt if you prefer the apt, can handle such situations.
If you do just

Code:

[sudo] apt upgrade

it is only upgrading already installed packages. if some have new dependencies you can install them using

Code:

[sudo] apt-get upgrade --with-new-pkgs

or with

Code:

[sudo] apt-get dist-upgrade

. the exclamation around "sudo" means that this is only needed if you aren't root.