Comment 8 for bug 1623087

This is related to https://bugs.launchpad.net/ubuntu/+source/apt/+bug/1634464 as well, where the maintainer says the "apt-key adv" is deprecated ("like everything else"). Not easy to understand what's deprecated.

By the way, "gpg --keyserver YYY --recv-key XXX" works 100% in Ubuntu Xenial, with no deprecation or warning whatsoever. It should not break in such unexpected way on Yakkety. It seems a gnupg->gnupg2 migration issue to me; I think that at least for Yakkety dirmngr should be included as a required dependency from gnupg2, a warning on the deprecation of such feature could be issues, then the dirmngr package could be switched to an optional dep LATER.

Even though IMHO such behaviour is still bad. If I do "gpg --help" in ubuntu yakkety, I clearly see the "--recv-keys" option. Then it breaks when using it if dirmngr is not installed. I would not list such option and let the user employ a different command altogether for fetching remote keys, instead: that would be WAY easier.

By the way, PLEASE consider that

"apt-key adv --keyserver ..."

is a VERY widely used and recommended command for installing keys. And some keyservers may not even expose a decent way of fetching public keys without the HKP protocol, making gpg --keyserver "the right choice".