Scenario - Master, and Slave Running on 2 VM's.
Master Wildfly - <replication-master cluster-name="my-cluster" group-name="srini-queues-cluster-group" check-for-live-server="true"/>
Slave Wildfly - <replication-slave cluster-name="my-cluster" group-name="srini-queues-cluster-group" allow-failback="false" max-saved-replicated-journal-size="1"/>

PFB below 2 errors.
At this time Slave will start deploying Queues even when Master wildfly is not stopped completely. Both management consoles can be reached.

Ideally, the Master server(Wildfly) should completely stop for Slave to start the deployment of queues and start the replication.

2019/01/16 19:56:21,118+05:30 ERROR [org.apache.activemq.artemis.core.server] (default I/O-2) AMQ224044: error acknowledging message: java.lang.NullPointer
Exception
at org.apache.activemq.artemis.core.server.impl.ServerConsumerImpl.removeReferenceByID(ServerConsumerImpl.java:811)

2019/01/16 19:56:21,121+05:30 ERROR [org.apache.activemq.artemis.core.server] (default I/O-2) AMQ224016: Caught exception: ActiveMQIllegalStateException[er
rorType=ILLEGAL_STATE message=null]
at org.apache.activemq.artemis.core.server.impl.ServerConsumerImpl.individualAcknowledge(ServerConsumerImpl.java:772)
at org.apache.activemq.artemis.core.server.impl.ServerSessionImpl.individualAcknowledge(ServerSessionImpl.java:739)

Detailed logs are attached.

At this stage, 1st component in my project pipeline has identified the slave as master now and stick with sending messages to it. Whereas the other components in the pipeline still consuming from Master(based on consumer count).

This caused the break-in message flow.