Doing a fresh install of osTicket v1.18.2.
I get to the point where I'm entering the database creation info and I get the Error 500 "currently unable to handle request."
Windows server 2019
MySQL 8.0.37
MariaDB 11.4.2
I've checked php, IIS and Windows logs and found no errors.

Any assistance appreciated.
EDIT: Turned on error reporting in bootstrap.php and got the errors below.
Fatal error: Uncaught Error: Call to undefined function mysqli_init() in C:\inetpub\wwwroot\include\mysqli.php:28 Stack trace: #0 C:\inetpub\wwwroot\setup\inc\class.installer.php(94): db_connect() #1 C:\inetpub\wwwroot\setup\install.php(52): Installer->install() #2 {main} thrown in C:\inetpub\wwwroot\include\mysqli.php on line 28