Symptoms
No logs are available in the /var/www/vhosts/example.com/logs directory for one or more domains
Cause
The hardlink that makes the log files appear in that directory is broken.
Resolution
Log into the server via SSH
Relink the logs directory by executing the following command:
Note: In an actual situation, example.com should be replaced with the affected domain):
# plesk db -Ne "select ss.login, d.name from sys_users ss
inner join hosting h
inner join domains d
where h.dom_id=d.id and h.sys_user_id=ss.id
and d.name='example.com'" | xargs -l bash -c '/usr/sbin/plesk sbin relink-vhost-logs --domain-name $1 --sys-user-login $0 --create'