Comment 5 for bug 1986458

You are a magician, yes it works now. Just an FYI, when I tried to add the PPA again I got:

Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8)).
Executing: /tmp/apt-key-gpghome.8vAgaO7yJX/gpg.1.sh --keyserver hkps://keyserver.ubuntu.com:443 --recv-keys 749CF4BDEC7B7CA1D1619EA092918F749165D72C

Which I fixed by running:

$ gpg --keyserver keyserver.ubuntu.com --recv 9165D72C
$ gpg --export --armor 9165D72C | sudo apt-key add && sudo apt update

and then I could add the PPA and install Bellepoule with no issue. Not sure if this was something specific to my machine or what I had done.

Thanks for all your help! Until the next mint release ;)