Plesk is installed on CloudLinux Server.
An attempt to install an application using Plesk Applications vault fails, download does not start, it stucks at 0%.
Synchronization of Service plan stuck, never stops.
The ptrace block is enabled on the server.
Such behavior cannot be considered as Plesk issue, because according to the CloudLinux Documentation ptrace protection may brake PSA service for Plesk 11.
To work around the issue disable ptrace protection by editing the
/etc/sysctl.conf file and adding the following line:
kernel.user_ptrace = 1
Then apply changes by executing the following command: