3797 Group Replication System Variables The value of this system variable can be changed while Group Replication is running, but the change only takes effect after you stop and restart Group Replication on the group member. group_replication_allow_local_lower_version_join  allows the current server to join the group even if it is running a lower MySQL Server version than the group. With the default setting OFF , servers are not permitted to join a replication group if they are running a lower version than the existing group members. This standard policy ensures that all members of a group are able to exchange messages and apply transactions. Note that members running MySQL 8.0.17 or higher take into account the patch version of the release when checking their compatibility. Members running MySQL 8.0.16 or lower, or MySQL 5.7, only take into account the major version. Set  group_replication_allow_local_lower_version_join  to  ON  only in the following scenarios: Setting this option to  ON  does not make the new member compatible with the group, and allows it to join the group without any safeguards against incompatible behaviors by the existing members. To ensure the new member’s correct operation, take  both  of the following precautions: Without these precautions, the server running the lower version is likely to experience difficulties and terminate with an error. Command-Line Format --group-replication-auto-increment- increment=# System Variable group_replication_auto_increment_increment Scope Global Dynamic Yes SET_VAR  Hint Applies No Type Integer Default Value 7 Minimum Value 1 • group_replication_auto_increment_increment 1. Before the server running the lower version joins the group, stop all writes on that server. 2. From the point where the server running the lower version joins the group, stop all writes on the other servers in the group. •You want to roll back an upgrade for one or more replication group members without shutting down the whole group and bootstrapping it again. •A server must be added to the group in an emergency in order to improve the group’s fault tolerance, and only older versions are available. Default Value OFF Warning