我正在尝试使用嵌入式Zookeeper建立具有三个节点的集群。这是我的配置：
zookeeper.properties：
server.1=192.168.0.104:2888:3888
server.2=192.168.0.101:2888:3888
server.3=192.168.0.102:2888:3888
state-management.xml：
<cluster-provider>
<id>zk-provider</id>
<class>org.apache.nifi.controller.state.providers.zookeeper.ZooKeeperStateProvider</class>
<property name="Connect String">192.168.0.104:2181,192.168.0.101:2181,192.168.0.102:2181</property>
<property name="Root Node">/nifi</property>
<property name="Session Timeout">10 seconds</property>
<property name="Access Control">Open</property>
</cluster-provider>
nifi.properties：
nifi.zookeeper.connect.string=192.168.0.104:2181,192.168.0.101:2181,192.168.0.102:2181
nifi.cluster.is.node=true
nifi.cluster.node.address=LOCAL_IP
nifi.cluster.node.protocol.port=3030
nifi.web.http.host=192.168.0.101
nifi.web.http.port=8080
nifi.remote.input.host=192.168.0.101
nifi.state.management.embedded.zookeeper.start=true
当我在选举后启动所有节点时，我的日志中出现以下错误：
2018-11-09 17:15:17,846 INFO [Reconnect to Cluster] o.a.nifi.controller.StandardFlowService Node disconnected due to Failed to properly handle Reconnection request due to org.apache.nifi.cluster.ConnectionException: Failed to connect node to cluster due to: java.lang.NullPointerException
2018-11-09 17:15:17,846 ERROR [Reconnect to Cluster] o.a.nifi.controller.StandardFlowService Handling reconnection request failed due to: org.apache.nifi.cluster.ConnectionException: Failed to connect node to cluster due to: java.lang.NullPointerException
org.apache.nifi.cluster.ConnectionException: Failed to connect node to cluster due to: java.lang.NullPointerException
at org.apache.nifi.controller.StandardFlowService.loadFromConnectionResponse(StandardFlowService.java:1009)
at org.apache.nifi.controller.StandardFlowService.handleReconnectionRequest(StandardFlowService.java:666)
at org.apache.nifi.controller.StandardFlowService.access$300(StandardFlowService.java:105)
at org.apache.nifi.controller.StandardFlowService$2.run(StandardFlowService.java:415)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException: null
at org.apache.nifi.controller.StandardFlowService.loadFromConnectionResponse(StandardFlowService.java:963)
... 4 common frames omitted
我已经检查了所有环境下的端口（已打开8080、3030、2181、2888、3888）。如何解决此错误？
在此先感谢您的帮助。