updates - Trying to upgrade to 16.04 from 15.10, but "the required dependency 'apt (>= 1.0.10.2ubuntu2)' is not installed"?

I tried sudo apt-get update, but got

E: Could not get lock /var/lib/apt/lists/lock - open (11: Resource temporarily unavailable)
E: Unable to lock directory /var/lib/apt/lists/
E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?

Any advice? Let me know if you need any more info.