IPv6 Support •Execute a  mysqladmin flush-hosts  command. This requires the  DROP  privilege for the Performance Schema  host_cache  table or the  RELOAD  privilege. •MySQL Server can accept TCP/IP connections from clients connecting over IPv6. For example, this command connects over IPv6 to the MySQL server on the local host: •Your system must be configured to support IPv6. See Section 5.1.13.1, “Verifying System Support for IPv6” . •The default MySQL server configuration permits IPv6 connections in addition to IPv4 connections. To change the default configuration, start the server with the  bind_address  system variable set to an appropriate value. See Section 5.1.8, “Server System Variables” . •MySQL account names permit IPv6 addresses to enable DBAs to specify privileges for clients that connect to the server over IPv6. See Section 6.2.4, “Specifying Account Names” . IPv6 addresses can be specified in account names in statements such as  CREATE USER ,  GRANT , and  REVOKE . For example: •IPv6 functions enable conversion between string and internal format IPv6 address formats, and checking whether values represent valid IPv6 addresses. For example,  INET6_ATON()  and  INET6_NTOA()  are similar to  INET_ATON()  and  INET_NTOA() , but handle IPv6 addresses in addition to IPv4 addresses. See Section 12.24, “Miscellaneous Functions” . •From MySQL 8.0.14, Group Replication group members can use IPv6 addresses for communications within the group. A group can contain a mix of members using IPv6 and members using IPv4. See Section 18.5.5, “Support For IPv6 And For Mixed IPv6 And IPv4 Groups” . 990 mysql>  CREATE USER ’bill’@’::1’ IDENTIFIED BY ’secret’; mysql>  GRANT SELECT ON mydb.* TO ’bill’@’::1’; To use this capability, two things must be true: shell>  mysql -h ::1 Support for IPv6 in MySQL includes these capabilities: Alternatively, to avoid having the error message occur, set  max_connect_errors  as described in Configuring the Host Cache. The default value of  max_connect_errors  is 100. Increasing max_connect_errors  to a large value makes it less likely that a host reaches the threshold and becomes blocked. However, if the  Host ’ host_name ’ is blocked  error message occurs, first verify that there is nothing wrong with TCP/IP connections from the blocked hosts. It does no good to increase the value of  max_connect_errors  if there are network problems. To unblock blocked hosts, flush the host cache; see Flushing the Host Cache. The value of the  max_connect_errors  system variable determines how many successive interrupted connection requests the server permits before blocking a host. After  max_connect_errors  failed requests without a successful connection, the server assumes that something is wrong (for example, that someone is trying to break in), and blocks the host from further connection requests. Host ’ host_name ’ is blocked because of many connection errors. Unblock with ’mysqladmin flush-hosts’ The server uses the host cache to track errors that occur during the client connection process. If the following error occurs, it means that  mysqld  has received many connection requests from the given host that were interrupted in the middle: Dealing with Blocked Hosts 5.1.13 IPv6 Support