So…. When trying to access one of my WordPress sites I got the message:
Your PHP installation appears to be missing the MySQL extension which is required by WordPress.
No problem I thought, must be a fault with PHP/Wordpress interaction, I’ll just upgrade to the latest version of WordPress. Oh, wait, I can’t access the WordPress dashboard – just get the same message.
I small amount of internet searching later and the solution was simple. I’m using Cpanel, so scrolled down to “Software” and clicked on “MultiPHP Manager”. Then I check the box against the domain causing an issue choose an earlier PHO version from the dropdown above, clicked Apply and… Hey Presto! Fixed – site and dashboard now work again.
I then upgraded WordPress via the dashboard and when done went back to “MultiPHP Manager” selected the relevant domain and reapplied “Inherit”.
I am having this problem when I’m upgrade the php from version 5.6 to 7.2. Turns out that mysql extension is no longer supported in php version 7.2. It is now using mysqli extention. I am using old version of wordpress which still using mysql extension so the problem existed. So what I did is upgraded the wordpress to the core. I used the latest version of wordpress and used filezilla to put the new version to the site. I only overwrite the folder wp-includes and wp-admin replace all the files in the root folder.