Exception 'IllegalArgumentException: Route Identifiers must be supplied' seen

when executing a flow programming test with mininet with 64 nodes, the following exception is seen:

java.lang.IllegalArgumentException: Route Identifiers must be supplied
at com.google.common.base.Preconditions.checkArgument(Preconditions.java:122)
at org.opendaylight.controller.remote.rpc.registry.RpcRegistry$Messages$ContainsRoute.<init>(RpcRegistry.java:139)
at org.opendaylight.controller.remote.rpc.registry.RpcRegistry$Messages$AddOrUpdateRoutes.<init>(RpcRegistry.java:160)
at org.opendaylight.controller.remote.rpc.RpcListener.onRpcAvailable(RpcListener.java:46)
at org.opendaylight.controller.md.sal.dom.broker.impl.DOMRpcRouter$3.run(DOMRpcRouter.java:104)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)

To reproduce:
1. Start mininet with 64 nodes and connect it to the controller
2. Blast 20k flows into the controller using flow config blaster:
./flow_config_blaster.py --auth --fpr 250 --flows 1000 --threads 20 --no-delete
3. Look at the logs