I have gone crazy to be able to configure GPG because of this error:
Healthcheck shell…Exception: data signing failed in
/var/www/passbolt/src/Utility/Healthchecks/GpgHealthchecks.php, line 304]
The problem is that php gpg2 can´t manage passphrases so you need to generate the keys without passphrase.
Hope nobody wastes more time with this issue. And, please, make an advice in installation guides to not use passphrase while generating the keys!!!