My site was down for a little over a day because I upgraded Plesk to version 9 on my VPS. It caused the PHP and Mysql adaptor to stop working. The site gave me this error:
Your PHP installation appears to be missing the MySQL extension which is required by WordPress.
It took me more about an hour Googling this to find out what the issue was. Plesk modified my php.ini fil while upgrading.
The guy that helped me the most was Donncha O Caoimh which his blog post on Holy Shmoly: “Cannot load mysql extension. Please check your PHP configuration“. I’m really glad he posted that. I’ve never met him, but he really helped me out.
Problem solved in less than an hour. 5 years ago, before the blogging explosion, this problem would have taken me days to resolve (at least!). Thanks to Donncha.