Firstly, it does not look like you are using the official raspberry pi
kernel for Xenial. Your kernel is 4.1, and the Xenial kernel is 4.4, so
it is possible that the kernel you are using does not have the required
apparmor bits that Ubuntu needs.
As for the error, does journalctl contain any
Public bug reported:
I get this logged in the journal every 30 seconds. Running Ubuntu Mate
16.10 on a raspberr pi2.
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: brltty 5.3.1-2ubuntu2.1
Uname: Linux 4.1.19-v7+ armv7l
ApportVersion: 2.20.1-0ubuntu2.4
Architecture: armhf
CurrentDesktop:
