Plesk: Scheduled Task for script not running

Symptoms: A task is scheduled in Plesk under Scheduled Tasks, the task attempts to run a php script but fails.

Solution:
By Default Plesk 11 does not allow execution of scripts in a non-chrooted environment,

To Allow execution of Scripts, change the server policy from the command prompt:

# /usr/local/psa/bin/server_pref -u -crontab-secure-shell “/bin/sh”

To disallow:
# /usr/local/psa/bin/server_pref -u -crontab-secure-shell “”

Plesk: Unable update mailbox: mailmng failed: Empty error message from utility

Symptom: When attempting to add a new mail account you receive the following error message: Unable update mailbox: mailmng failed: Empty error message from utility

Solution: The error is caused by a security update released in Ubuntu for mysql 5.1.66, there is currently no Plesk fix for this error as of Nov. 13th, 2012. In order to resolve the error you must roll back 5.1.66 to 5.1.63.

Instructions can be found here for the temporary fix: Parallels Forum

Note: If Ubuntu 10.04 LTS is set to automatically install updates, every time it checks for updates it will patch 5.1.63 to 5.1.66 again.