My website is now not opening with the above error message. A search of the forum suggests that this is a common problem and a solution is suggested that the php-mysql module is not installed (eg https://forum.WebsiteBaker.org/index.php/topic,22117.msg149087.html#msg149087. Is this something the hosting provider should install? The site has been working until recently, it is using WBv2.12.2 and PHP v7.3.
I have emailed the hosting provider support line but still await a reply.
Sometimes there are also server problems.
The hoster will tell more and will know more.