Phase 4: Upgrade the remaining nodes
After the first node has been successfully upgraded, you should proceed with upgrading the remaining nodes according to your planned upgrade order.
At the end of this phase:
All nodes are upgraded to the new version of Cassandra and are functioning normally.
Any applications connecting to the cluster are functioning normally.
If there are service issues at this point, decide whether or not to proceed with remaining upgrade steps. For further details, see Phase 5: Decide to continue or abandon the upgrade.