I also recognized, that there are no new previews generated for my nextcloud, where the cronjob is done successfully every hour.
But the command is correct. If you try
sudo -u www-data php /var/www/owncloud/oc preview:PreGenerate you will get
Command "preview:PreGenerate" is not defined.
Did you mean one of these?
I don’t know where these commands are defined, but they are. I try
preview:generate-all at the moment. It takes time, so seems to be promising. Maybe pre-generate does only work for new files or something to not always need to scan the wohl data directories.
preview:generate-all is still working while i am typing. I will give you results, when it’s done .