This is the fix.
on Ubuntu 18.04: This is what works:
Worked from command line to install:
sudo -u www-data php occ app:install twofactor_adminWorked to get me the codes to unlock everybody “one at a time”:
sudo -u www-data php occ twofactorauth:admin:generate-code username
Refer –
https://help.nextcloud.com/t/how-to-disable-2-factor-authentication-on-command-line-installed-twofactor-email-now-cant-login/57363
https://docs.nextcloud.com/server/16/admin_manual/configuration_server/occ_command.html?highlight=occ#two-factor-auth-label