Re: Problems with apt in a clean stretch install.
> > Read this:
> > https://unix.stackexchange.com/questions/75807/no-public-key-available-on-apt-get-update
> Thanks. Yeah I have tried importing keys (even though they already exist as confirmed with 'apt-key list' and it makes no difference. All the keys complained about are already present.
> I don't have enough experience nor understanding of Linux to know whether it's a bug or dumb user and though I suspect the latter, I feel like there's a chance it could be the former.
Hmmm I use Jessie for last years, with no any experience with Strech
yet. But I feel you have some problem(s) with sources.list or with apt
file(s) privileges somehow/somewhere.
In this link before, there is something more - did You try to install
debian-keyring (before was debian-archive-keyring)?