Comment 5 for bug 1756800

No, the script is returning non-zero because some of the profiles didn't load, but the rest of the profiles will load fine. You can prove this to yourself using 'sudo aa-status'.

As for those two profiles, the come from https://launchpad.net/ubuntu/+source/webbrowser-app/ and https://launchpad.net/ubuntu/+source/mediascanner2/, both of which have been removed from 18.04. It sounds like these packages are still installed on you system, you can remove them with:

$ sudo apt-get remove --purge webbrowser-app mediascanner2.0