I’ve wasted a lot of time worrying about why an emacs init.el startup config that works on my aged Ubuntu box doesn’t work on Debian 10, if I try to refresh the packages from ‘Melpa’ (the solution is just as horrible.)
(setq gnutls-algorithm-priority “NORMAL:-VERS-TLS1.3”)
Huge thanks to:
for taking the time to share the results of a personal investment of time.
I don’t think I would have guessed that 
Much of the wasted time was because I got the same message when I had an expired GPG public key problem on Ubuntu, so I’ve been looking for the wrong problem.
At least I’ve learned it would be a good idea to put my working emacs config into git :-/