Upgrade Script Netrunner 17 -> Ubuntu Xenial (16.04 LTS) base

I get this error when trying to update the Package Installer:

The repository ‘http://ppa.launchpad.net/n-muench/programs-ppa/ubuntu xenial Release’ does not have a Release file.Data from such a repository can’t be authenticated and is therefore potentially dangerous to use.See apt-secure(8) manpage for repository creation and user configuration details.Failed to fetch http://ppa.launchpad.net/n-muench/programs-ppa/ubuntu/dists/xenial/main/binary-amd64/Packages 404 Not FoundSome index files failed to download. They have been ignored, or old ones used instead.

This seems to be a third party ppa that you added to Netrunner 17 and it isn’t releasing any software for xenial.
I advise deactivating it.

I have thank you