MySQL 8 Administrator???s Guide

Host host_name is blocked

If the mysqld server receives too many connection requests from the host that is interrupted in the middle, the following error occurs:

Host 'host_name' is blocked because of many connection errors.Unblock with 'mysqladmin flush-hosts'

The max_connect_errors system variable determines the number of successive interrupted connection requests that are allowed. Once there are max_connect_errors failed requests without a successful connection, mysqld assumes that something is wrong and blocks the host from further connections until the FLUSH HOSTS statement or mysqladmin flush-hosts command is issued.

mysqld blocks a host after 100 connection errors as a default. It can be adjusted by setting the max_connect_errors