During 3node testing using graceful start and stop the following exception is seen. Graceful start and stop means using the bin/stop and start commands to stop and start ODL rather than using kill -9. This means there is an orderly stop to the bundles where each bundle is destroyed. Some bundles in ovsdb are destroyed and the exceptions start.
The flow is all three ODLs are up. Then shutdown ODL1 via bin/stop. Start ODL1, Stop ODL2, start ODL2. Cluster is good then take down ODL3. ODL happens to be the leader. These exception below repeats until ODL3 is restarted.