It looks as though there is a failing attempt to upgrade some of the Mir libraries (probably Mir 0.24 to Mir 0.26) as IIRC the 16.04.2 shipped before that update in the archive.
If that theory is correct, it will be fixed by:
$ sudo apt dist-upgrade
In addition, it shouldn't happen with the current ubuntu-16.04.3-desktop-amd64.iso
It looks as though there is a failing attempt to upgrade some of the Mir libraries (probably Mir 0.24 to Mir 0.26) as IIRC the 16.04.2 shipped before that update in the archive.
If that theory is correct, it will be fixed by:
$ sudo apt dist-upgrade
In addition, it shouldn't happen with the current ubuntu- 16.04.3- desktop- amd64.iso