title: gpg: no valid OpenPGP data found after update
body: <p>I recently upgraded my base system and now gpg with version 2.1.x is in use. Unfortunately it does not read my old keyrings any more.
  As I see from <a href="https://www.gnupg.org/faq/whats-new-in-2.1.html" rel="nofollow noreferrer">here</a> the gpg system should convert it automatically, however this is not happening in my Ubuntu. How can the old format converted then manually?</p>