Unable to install application in Plesk on CloudLinux server: mysqli extension was not found

Updated: 11 October 2026 · Applies to: Plesk Obsidian 18.0

On Plesk servers with CloudLinux alt-PHP and CageFS, installing or updating applications can hang or fail because alt-PHP lacks the mysqli extension.

Workaround (root)

1. In Plesk, open Tools & Settings › PHP Settings, choose the alt-php version and edit its php.ini.
2. Add at the end:

   extension=mysqlnd.so
   extension=mysqli.so

3. Update PHP settings for all domains: plesk bin php_settings -u.

Check with php -m for that PHP version. Keep Plesk and CloudLinux updated, as later versions address this.