Zend certified PHP/Magento developer

Magento 1.9 Fatal error: Interface ‘Zend_Session_SaveHandler_Interface’ not found

I migrated from a cpanel hosting to plesk hosting, going thru error by error and resolving them.

Right now facing a bottleneck when trying to login to admin backend it results in error as below.

Fatal error: Interface 'Zend_Session_SaveHandler_Interface' not found in /var/www/vhosts/site/app/code/core/Mage/Core/Model/Resource/Session.php on line 35

Any ideas?

Ps, I know of magento2 & up to date versions etc. but its client requirement to use the legacy version for now.

J