Transactions not supported in 'mysql' driver. Use 'mysqlt' or 'mysqli' driver

Since a couple of days a have an error with several forms that send a mail to users. is this new?

Transactions not supported in ‘mysql’ driver. Use ‘mysqlt’ or ‘mysqli’ driver

look maybe there, in case off;
https://www.php.net/manual/en/ref.pdo-mysql.php

Have you upgraded PHP to 7.4? The mysql functions are deprecated a long time. You can try to use another driver (non transactional) or report to SC?

Still mysql 7.1 nothing changed.

Do your other queries to the mySQL db work? Did you recently rebuild the DB? If so, check the storage engine - the InnoDB engine supports transactions but the ISAM does not.

The mysqli driver is what your code should be using to be compatible with currently supported versions of PHP. I am not sure what version of PHP you are speaking of - is it 7.1 or is the mySQL DB 7.1?

nothing has changed. the mysqldb is 7.1 all the other query’s work