Hello,
we faced the following problem after running this sequence:
Our cluster was running well for 24h on a single machine then one node was detected as dead (without any obvious reason). Anyway, the node was shutdown as it discovered it was ejected from the cluster view. Then, the coordinator get this error :

05:58:20,613 WARN [NAKACK][UpHandler (NAKACK)] 130.22.107.60:33612] discarded message from non-member 130.22.107.60:33618, my view is [130.22.107.60:33612|5] [130.22.107.60:33612, 130.22.107.60:33616, 130.22.107.60:33622, 130.22.107.60:33624]
05:58:21,612 WARN [NAKACK][UpHandler (NAKACK)] 130.22.107.60:33612] discarded message from non-member 130.22.107.60:33618, my view is [130.22.107.60:33612|5] [130.22.107.60:33612, 130.22.107.60:33616, 130.22.107.60:33622, 130.22.107.60:33624]
05:58:22,618 WARN [NAKACK][UpHandler (NAKACK)] 130.22.107.60:33612] discarded message from non-member 130.22.107.60:33618, my view is [130.22.107.60:33612|5] [130.22.107.60:33612, 130.22.107.60:33616, 130.22.107.60:33622, 130.22.107.60:33624]
05:58:23,628 WARN [NAKACK][UpHandler (NAKACK)] 130.22.107.60:33612] discarded message from non-member 130.22.107.60:33618, my view is [130.22.107.60:33612|5] [130.22.107.60:33612, 130.22.107.60:33616, 130.22.107.60:33622, 130.22.107.60:33624]
05:58:25,369 ERROR [DownHandler][DownHandler (STATE_TRANSFER)] DownHandler (STATE_TRANSFER) caught exception
java.lang.NullPointerException
at org.jgroups.protocols.pbcast.STATE_TRANSFER.down(STATE_TRANSFER.java:252)
at org.jgroups.stack.DownHandler.run(Protocol.java:121)

(the member with the JGadress 130.22.107.60:33618 is the one that failed)

May we know what causes this error and how to correct it ?
Regards