The other day I had a problem upgrading my machine. No matter what I tried I continually got an error like this:
files list file for package 'libvpx0' is missing final newline

I left it alone, figuring that it was a package-related problem, but it persisted for a few days. A bit of Googling turned up this page: http://www.linuxquestions.org/questions/debian-26/apt-get-dpkg-error-files-list-file-missing-final-newline-271118/ which provides the answer.

It turns out I had two corrupted list files: /var/lib/dpkg/info/libvpx0.list and /var/lib/dpkg/info/libtiff4.list. I removed the list files and ran apt-get upgrade again and everything happily upgraded.

So, "missing newline" problem is solved by removing the offending .list file from /var/lib/dpkg/info