Resolved Can't install plesk firewall or ModSecurity & Fail2ban

[Space Monkey]

Plesk firewall always gives this error: Could not install the following component(s) "psa-firewall". The operation was locked by another update process. Please try again later.

ModSecurity & Fail2ban always directs a page that doesn't load.

Which one of the too uses the least ram and how can I resolve the issue?

 

[IgorG]

This issue can be resolved by following the instructions posted in this KB -
Plesk Installer: Update operation was locked by another update process