Server sent charset unknown to the client. Please, report to the developers

[questions]

Connect the lower version of PHP to the higher version of MySQL (such as mysql8.0)

Server sent charset unknown to the client. Please, report to the developers

[solution]

Method (1): upgrade the PHP connection driver

Method (2): put mysql8.0   Change the parameter of character_set_server to utf8 (it cannot be changed online. You need to modify my.cnf and restart Mysql to take effect)