The following command in Ubuntu 18.04 on a DO droplet is returning the error 'Invalid argument':
apt-key adv --fetch-keys 'https://mariadb.org/mariadb_release_signing_key.asc'
I've checked the contents of /etc/apt/ and there's no file trusted.gpg but there is a directory trusted.gpg.d that contains 6 gpg files: dovecot.gpg, 1st_debian_repo.gpg, ubuntu-keyring-2012-archive.gpg, ubuntu-keyring-2012-cdimage.gpg, ubuntu-keyring-2018-archive.gpg
Any ideas please for a linux novice? Should I somehow remove all keys and start again?
