Private chain nodes would not do Consensus about neo-node HOT 5 CLOSED

neo>start consensus
[15:11:25] OnStart
[15:11:25] initialize: height=1 view=0 index=2 role=Backup
[15:11:53] OnChangeViewReceived: height=1 view=0 index=0 nv=1
[15:11:55] timeout: height=1 view=0 state=Backup
[15:11:55] request change view: height=1 view=0 nv=1 state=Backup, ViewChanging
[15:12:52] OnChangeViewReceived: height=1 view=0 index=0 nv=2
[15:12:55] timeout: height=1 view=0 state=Backup, ViewChanging
[15:12:55] request change view: height=1 view=0 nv=2 state=Backup, ViewChanging
show state
Height: 0/0, Nodes: 1
15:14:52] OnChangeViewReceived: height=1 view=0 index=0 nv=3
[15:14:55] timeout: height=1 view=0 state=Backup, ViewChanging
[15:14:55] request change view: height=1 view=0 nv=3 state=Backup, ViewChanging

neo>start consensus
[11:34:00] OnStart
[11:34:00] initialize: height=1 view=0 index=3 role=Backup
[11:34:31] timeout: height=1 view=0 state=Backup
[11:34:31] request change view: height=1 view=0 nv=1 state=Backup, ViewChanging
[11:35:31] timeout: height=1 view=0 state=Backup, ViewChanging
[11:35:31] request change view: height=1 view=0 nv=2 state=Backup, ViewChanging
[11:35:35] OnChangeViewReceived: height=1 view=1 index=2 nv=2
[11:35:44] OnChangeViewReceived: height=1 view=0 index=0 nv=1
show state
Height: 0/4002, Nodes: 2
show node
::ffff:162.243.8.59 port:54619 listen:10333 [1/2]
::ffff:162.243.192.197 port:43796 listen:0 [2/2]
[11:36:43] OnChangeViewReceived: height=1 view=0 index=0 nv=2
[11:36:43] initialize: height=1 view=2 index=3 role=Primary
[11:36:43] timeout: height=1 view=2 state=Primary
[11:36:43] send perpare request: height=1 view=2

Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object.
   at Neo.Consensus.ConsensusService.OnTimeout(Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.TimerQueueTimer.CallCallback()
   at System.Threading.TimerQueueTimer.Fire()
   at System.Threading.TimerQueue.FireNextTimers()
Aborted (core dumped)