Deploying Group Replication in Single-Primary Mode Adding additional instances to the group is essentially the same sequence of steps as adding the second server, except that the configuration has to be changed as it had to be for server s2. To summarise the required commands: If you are providing user credentials using a  CHANGE REPLICATION SOURCE TO  |  CHANGE MASTER TO  statement, issue the following statement after that: Or if you are providing user credentials for distributed recovery on the  START GROUP_REPLICATION statement (which you can from MySQL 8.0.21): 3713 mysql>  START GROUP_REPLICATION USER=’ rpl_user ’, PASSWORD=’ password ’; mysql>  START GROUP_REPLICATION; INSTALL PLUGIN group_replication SONAME ’group_replication.so’; CHANGE MASTER TO MASTER_USER=’ rpl_user ’, MASTER_PASSWORD=’ password ’ \\  FOR CHANNEL ’group_replication_recovery’; Or from MySQL 8.0.23: CHANGE REPLICATION SOURCE TO SOURCE_USER=’ rpl_user ’, SOURCE_PASSWORD=’ password ’ \\  FOR CHANNEL ’group_replication_recovery’; SET SQL_LOG_BIN=0; CREATE USER  rpl_user @’%’ IDENTIFIED BY ’ password ’; GRANT REPLICATION SLAVE ON *.* TO  rpl_user @’%’; GRANT BACKUP_ADMIN ON *.* TO  rpl_user @’%’; FLUSH PRIVILEGES; SET SQL_LOG_BIN=1; [mysqld] # # Disable other storage engines # disabled_storage_engines="MyISAM,BLACKHOLE,FEDERATED,ARCHIVE,MEMORY" # # Replication configuration parameters # server_id=3 gtid_mode=ON enforce_gtid_consistency=ON binlog_checksum=NONE # Not needed from 8.0.21 # # Group Replication configuration # plugin_load_add=’group_replication.so’ group_replication_group_name="aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa" group_replication_start_on_boot=off group_replication_local_address= "s3:33061" group_replication_group_seeds= "s1:33061,s2:33061,s3:33061" group_replication_bootstrap_group= off 1. Create the configuration file. 2. Start the server and connect to it. Create the replication user for distributed recovery. 3. Install the Group Replication plugin if necessary. 4. Start Group Replication.