When Plesk starts performing a backup, it reports the progress to a log. Backup logs contain only general errors such as syntax errors (no or wrong command specified, invalid input parameters), runtime errors and unhandled exceptions, low disk space for backup, and so on.
Each backup log is located in a separate folder that contains date and time of the backup in its name. Backup logs are stored in the following locations:
/*.log in Plesk for Linux
/*.log in Plesk for WIndows
YYYY-MM-DD-hh-mm-ss is the date and time when the backup was created and
nnn is a randomly generated number.
You can change the level of details included into logs. This feature is available only for scheduled backups and for backups made through command line. For more information on how to change level of details, see the Advanced Administration Guide for Plesk for Linux or Windows.