issues with preg_replace() and missing 'mysql' adapter

[grimoirelll]

I'm getting errors having installed Zencart 1.56 as a sub domain to Joomla 1.5.6.
The main domain went down and the following errors are posting.

Warning: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead in /home1/isexcorp/public_html/insightnews/libraries/joomla/filter/input.php on line 652

Warning: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead in /home1/isexcorp/public_html/insightnews/libraries/joomla/filter/input.php on line 654
Database connection error (1): The MySQL adapter 'mysql' is not available.Database connection error (1): The MySQL adapter 'mysql' is not available.


Question:
Is it possible to get The MySQL adapter 'mysql' is not available.Database connection error (1): The MySQL adapter 'mysql' is not available.

The adapter?

[toivo]

The site seems to be using PHP 7 because the warning about the /e modifier started from PHP 7.0. Suppressing warnings will not help because PHP 7 supports only the 'mysqli' adapter instead of 'mysql'.

Unless you can revert back to an earlier version of PHP, which is not recommended, you need to start planning a migration to a supported version of Joomla. The latest version is now 3.9.3 and the Migrating and Upgrading forum has the necessary guides at viewforum.php?f=710