Already solved.
If upon client reconnection you get the following error.
2020.09.03 17:55:16 ERROR [socket_c2s-thread-5]: org.jivesoftware.openfire.nio.ConnectionHandler - Closing connection due to error while processing message:
java.lang.NullPointerException: Domain cannot be null
at org.xmpp.packet.JID.(JID.java:506) ~[tinder-2.0.0.jar:?]
at org.jivesoftware.openfire.streammanagement.StreamManager.startResume(StreamManager.java:254) ~[xmppserver-4.4.4.jar:4.4.4]
at org.jivesoftware.openfire.streammanagement.StreamManager.process(StreamManager.java:135) ~[xmppserver-4.4.4.jar:4.4.4]
at org.jivesoftware.openfire.net.StanzaHandler.process(StanzaHandler.java:198) ~[xmppserver-4.4.4.jar:4.4.4]
You just need to set the system property “xmpp.domain” for the installation script.