MemSql leaf down on Single server Cluster -

i have single server cluster installation of memsql on ubuntu 14 lts. unable connect memsql on port 3306 cluster running on port 9000. looks leaf down. when tried upgrade memsql version 4.0.1 got error:-

starting memsql upgrade on state offlineclusterupgrade.init on state offlineclusterupgrade.snapshottingdatabases on state offlineclusterupgrade.offlineclusterupgradefail memsql node 8d84f89d6716f03a44eacb9e3af6565fa76b9de9 failed upgrade: not connect memsql node 8d84f89d6716f03a44eacb9e3af6565fa76b9de9. memsql node online? 

what can bring memsql again?

the cluster manager provided on port 9000. firstly showed status of nodes.

there alert icon clicking showed solution.

i ran command

memsql-ops cluster-start

it caused node recover , start again. good.