Troubleshooting database issues

Version 9 of WebMail Pro requires MySQL 5.7.8 or newer / MariaDB 10.2.7 or newer, with mysqlnd driver.

One of the signs of having an outdated driver is InvalidArgumentException shown in debug logs, which occurs due to unexpected data type returned. Switching to mysqlnd driver should resolve that.

To check if you have a correct driver, you can create PHP script in WebMail Pro directory, with the following code there:

<?php phpinfo();

Run it from web browser and check the output for "Client API library version" under mysqli section and for "Client API version" in pdo_mysql section. Both the values should include "mysqlnd", for example:

If there's no "mysqlnd" in either of the above, that means mysqlnd driver isn't enabled. Reconfigure your PHP environment to enable it; if you're using a control panel of some kind, see if it offers mysqlnd in the list of PHP features / extensions available. For example, in case of cPanel look for nd_mysql and nd_pdo_mysql options.