How to enable debug output in Parallels Plesk Panel to troubleshoot APS packages?
Log level can be increased in Plesk's panel.ini file:
Windows: C:\\Program Files (x86)\\Parallels\\Plesk\\admin\\conf\\panel.ini
Set the maximum verbosity as follows:
filter.priority = 7
The resulting log file can be found:
Windows: C:\\Program Files (x86)\\Parallels\\Plesk\\admin\\logs\\panel.log
If APS operations should fail, resulting output from APS package script can be found in this log.