- Plesk for Linux
PHP 5.6 is missing from Plesk Installer.
Is it possible to install PHP 5.x in Plesk on Debian 9 and Ubuntu 18.04 via Plesk Installer?
It is not possible to install PHP 5.x via Plesk Installer.
By default, Debian 9 and Ubuntu 18.04 support only PHP 7.x compatible with OpenSSL 1.1.
As a workaround, consider adding them as a custom PHP according to the article.