When we run campaign in 7.13 version, and when we run campaign getting below errors like below. This does not happen all the time, but it's very frequent. 

Would you please check and help me to understand the root cause?

com.pega.dsm.dnode.impl.core.ExceptionWithInputRecord: com.pega.dsm.dnode.api.DNodeException: Cannot execute modification statement at com.pega.dsm.dnode.impl.dataflow.strategy.StrategyStageProcessor.onNext(StrategyStageProcessor.java:151) at com.pega.dsm.dnode.api.dataflow.DataFlowStageBatchProcessor.commitBatchInternal(DataFlowStageBatchProcessor.java:102) at com.pega.dsm.dnode.api.dataflow.DataFlowStageBatchProcessor.commitBatch(DataFlowStageBatchProcessor.java:92) at com.pega.dsm.dnode.api.dataflow.DataFlowStageBatchProcessor.onCompleted(DataFlowStageBatchProcessor.java:78) at com.pega.dsm.dnode.api.dataflow.DataFlowStage$StageInputSubscriber.onCompleted(DataFlowStage.java:302) at com.pega.dsm.dnode.api.dataflow.DataFlowExecutor$QueueBasedDataFlowExecutor$4.process(DataFlowExecutor.java:213) at com.pega.dsm.dnode.api.dataflow.DataFlowExecutor$QueueBasedDataFlowExecutor.runEventLoop(DataFlowExecutor.java:119) at com.pega.dsm.dnode.api.dataflow.DataFlow$1.emit(DataFlow.java:162) at com.pega.dsm.dnode.impl.stream.DataObservableImpl.subscribe(DataObservableImpl.java:56) at com.pega.dsm.dnode.impl.dataflow.manager.LocalRun.execute(LocalRun.java:145) at com.pega.dsm.dnode.impl.dataflow.manager.LocalRun.lockAndRun(LocalRun.java:86) at com.pega.dsm.dnode.impl.dataflow.manager.LocalRun.run(LocalRun.java:63) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at com.pega.dsm.dnode.impl.prpc.PrpcThreadFactory$PrpcThread.run(PrpcThreadFactory.java:81) Caused by: com.pega.dsm.dnode.api.DNodeException: Cannot execute modification statement at com.pega.dsm.dnode.impl.cassandra.CassandraDao.executeStatement(CassandraDao.java:172) at