2017-11-28 06:24:39,649 | ERROR | eChangeHandler-6 | AsyncDataTreeChangeListenerBase  | 247 - org.opendaylight.genius.mdsalutil-api - 0.4.0.SNAPSHOT | Thread terminated due to uncaught exception: org.opendaylight.yang.gen.v1.urn.opendaylight.neutron.ports.rev150712.ports.attributes.ports.Port_AsyncDataTreeChangeListenerBase-DataTreeChangeHandler-6
java.lang.NullPointerException
	at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1645)[:1.8.0_151]
	at org.opendaylight.netvirt.ipv6service.VirtualNetwork.updateDpnPortInfo(VirtualNetwork.java:38)[333:org.opendaylight.netvirt.ipv6service-impl:0.6.0.SNAPSHOT]
	at org.opendaylight.netvirt.ipv6service.IfMgr.removePort(IfMgr.java:465)[333:org.opendaylight.netvirt.ipv6service-impl:0.6.0.SNAPSHOT]
	at org.opendaylight.netvirt.ipv6service.NeutronPortChangeListener.remove(NeutronPortChangeListener.java:81)[333:org.opendaylight.netvirt.ipv6service-impl:0.6.0.SNAPSHOT]
	at org.opendaylight.netvirt.ipv6service.NeutronPortChangeListener.remove(NeutronPortChangeListener.java:30)[333:org.opendaylight.netvirt.ipv6service-impl:0.6.0.SNAPSHOT]
	at org.opendaylight.genius.datastoreutils.AsyncDataTreeChangeListenerBase$DataTreeChangeHandler.run(AsyncDataTreeChangeListenerBase.java:143)[247:org.opendaylight.genius.mdsalutil-api:0.4.0.SNAPSHOT]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)[:1.8.0_151]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)[:1.8.0_151]
	at java.lang.Thread.run(Thread.java:748)[:1.8.0_151]