Upgrade to Database 5.7 — mixed version clusters

When executing a rolling upgrade from Database 5.6, you must wait for migrations to complete before moving on to upgrade the next cluster node. Do not add or permanently remove cluster nodes before the upgrade to 5.7 is complete across the entire cluster. Failing to do so can result in records that fail to be indexed correctly by secondary indexes. This issue will not manifest if the cluster nodes remain the same and migrations settle between node upgrades.

For more information about Database 5.7, see the Release Notes.