Github user thenatog commented on the issue:
https://github.com/apache/nifi/pull/3034
> Hey,
>
> I'm facing this issue while trying to upgrade from 1.6.0 to 1.8.0.
>
> PFB the logs
>
> ```
> 2018-11-30 15:36:58,500 WARN [Process Cluster Protocol Request-2]
org.apache.nifi.io.socket.SocketListener Dispatching socket request encountered
exception due to: java.lang.NullPointerException
> java.lang.NullPointerException: null
> 2018-11-30 15:36:58,500 WARN [Process Cluster Protocol Request-1]
org.apache.nifi.io.socket.SocketListener Dispatching socket request encountered
exception due to: java.lang.NullPointerException
> java.lang.NullPointerException: null
> 2018-11-30 15:36:58,647 WARN [main]
o.a.nifi.controller.StandardFlowService Failed to connect to cluster due to:
java.lang.NullPointerException
> ```
> This are WARN logs but the node doesn't connect to the cluster when doing
a rolling restart of the servers.
Was there a reason you replied to this PR specifically? This PR was
submitted to suppress specific warning logs Jetty was producing.
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