This section describes how to upgrade a Neo4j HA cluster.
Upgrading a Neo4j HA cluster requires following a specific process in order to ensure that the cluster remains consistent, and that all cluster instances are able to join and participate in the cluster following their upgrade.
Shut down the cluster
Upgrade the master
dbms.mode=SINGLEin neo4j.conf to disable HA in the configuration.
dbms.mode=HAin neo4j.conf to re-enable HA in the configuration.
Make a full backup of the Neo4j database.
Please note that backups taken before the upgrade are no longer valid for update via the incremental online backup. Therefore, it is important to perform a full backup, using an empty target directory, at this point.
Upgrade the slaves
On each slave:
If applicable, copy the security configuration from the master, since this is not propagated automatically.
Alternatively, at this point you can manually copy the database directory from the master to the slaves. Doing so will avoid the need to sync from the master when starting. This can save considerable time when upgrading large databases.
Restart the cluster
Start the slaves, one by one.
Once a slave has joined the cluster, it will sync the database from the master instance.