[IP.Board 3.1.3 / PHP 7.2] «Use of undefined constant SQL_DRIVER in admin/applications/core/modules_admin/diagnostics/diagnostics.php on line 911»

How to fix

Locate the line in the admin/applications/core/modules_admin/diagnostics/diagnostics.php file:

'sql_driver'  => strtoupper(SQL_DRIVER),

Replace it with:

'sql_driver'  => strtoupper(IPSSetUp::getSavedData('sql_driver')),

Add the following line at the beginning of the _listFunctions() method:

require_once(IPS_ROOT_PATH . '/setup/sources/base/setup.php');