Recently we faced the below error while trying to install MagicSpam free version via plesk interface and got installed via command line using the rpm from the plesk download section. Since the plesk download section had too old version and plesk was showing an upgrade option and free version was not working (which I installed from rpm available at plesk )
Error while trying to install / upgrade from plesk interface is the below
Failed Installation of extension has failed Execution of /usr/local/psa/tmp/modulehfmXQh/plib/scripts/pre-install.php failed with exit code 1 and the output: Failed to find operating system package manager rpm or dpkg. Contact [email protected] with full details of your installation for assistance.
Normal rpm installation and yum install was working fine.