Help: Copied gnupg folder not recognised

[David Seaward]

Hi,

I copied ~/.gnupg from my old machine, because I want to copy all keys,
trust data etc. [1]

However, on my new machine, nothing seems to be recognising the GnuPG
files:

* "gnupg --list-keys" is empty ("gnupg --help" confirms that ~/.gnupg
is the folder being used)

* The "GnuPG keys" pane of "GNOME Password and Keys" is empty

* Email client is not able to encrypt/decrypt messages

How can I diagnose what the problem is? Failing that, how can I
export/import an entire .gnupg folder (including trust data)?

Regards,
David

[1] https://www.phildev.net/pgp/gpg_moving_keys.html