Shard currently has no leader. Try again later.

This is happening in CSIT [0] for module-based shards with tell-based protocol, after long period of isolation. It is possible that suite logic is not correct [1].

After fixing the suite, a real bug might become visible, as karaf.log [2] shows multiple messages such as:
2017-05-14 06:26:44,925 | INFO | ult-dispatcher-3 | Shard | 192 - org.opendaylight.controller.sal-clustering-commons - 1.5.0.Carbon | member-3-shard-default-config (Leader): handleAppendEntriesReply - received unsuccessful reply: AppendEntriesReply [term=7, success=false, followerId=member-2-shard-default-config, logLastIndex=3561, logLastTerm=3, forceInstallSnapshot=false, payloadVersion=5, raftVersion=3], leader snapshotIndex: 41

That might be preventing the new writer from functioning correctly.

[0] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-clustering-only-carbon/684/archives/log.html.gz#s1-s33-t2-k2-k23-k1-k8-k1-k1-k1
[1] https://git.opendaylight.org/gerrit/#/c/56651/3/csit/libraries/controller/DdbCommons.robot@188
[2] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-clustering-only-carbon/684/archives/odl3_karaf.log.gz