Group Replication Online Upgrade relies on an asynchronous replication channel which is used to replicate data from one group to another, it is supported under the same assumptions and requirements of asynchronous source-replica replication, see Chapter 17,  Replication . For groups operating in single-primary mode, the asynchronous replication connection to the old group must send data to the primary in the new group, for a multi-primary group the asynchronous replication channel can connect to any primary. The process is to: Before you can redirect your application to the new group, you must ensure that the new group has a suitable number of members, for example so that the group can handle the failure of a member. Issue SELECT * FROM performance_schema.replication_group_members  and compare the initial group size and the new group size. Wait until all data from the old group is propagated to the new group and then drop the asynchronous replication connection and upgrade any missing members. •remove members from the original group running the older server version one by one, see Section 18.8.3.2, “Upgrading a Group Replication Member” •upgrade the server version running on the member, see Section 2.11, “Upgrading MySQL” . You can either follow an in-place or provision approach to upgrading. •create a new group with the upgraded members, see Chapter 18,  Group Replication . In this case you need to configure a new group name on each member (because the old group is still running and using the old name), bootstrap an initial upgraded member, and then add the remaining upgraded members. •set up an asynchronous replication channel between the old group and the new group, see Section 17.1.3.4, “Setting Up Replication Using GTIDs” . Configure the older primary to function as the asynchronous replication source server and the new group member as a GTID-based replica. Rolling Duplication Upgrade In this method you create a second group consisting of members which are running the newer version, and the data missing from the older group is replicated to the newer group. This assumes that you have enough servers to run both groups simultaneously. Due to the fact that during this process the number of primaries is  not  decreased, for groups operating in multi-primary mode there is no reduction in write availability. This makes rolling duplication upgrade well suited to groups operating in multi-primary mode. This does not impact groups operating in single-primary mode. Because the group running the older version is online while you are provisioning the members in the new group, you need the group running the newer version to catch up with any transactions executed while the members were being provisioned. Therefore one of the servers in the new group is configured as a replica of a primary from the older group. This ensures that the new group catches up with the older group. Because this method relies on an asynchronous replication channel which is used to replicate data from one group to another, it is supported under the same assumptions and requirements of asynchronous source-replica replication, see Chapter 17,  Replication . For groups operating in single-primary mode, the asynchronous replication connection to the old group must send data to the primary in the new group, for a multi-primary group the asynchronous replication channel can connect to any primary. The process is to: •deploy a suitable number of members so that the group running the newer version can handle failure of a member •take a backup of the existing data from a member of the group •use the backup from the older member to provision the members of the new group, see Section 18.8.3.4, “Group Replication Upgrade with  mysqlbackup ”  for one method. 3792