java.lang.AssertionError: Wrong class type.
        at org.apache.cassandra.db.BufferCounterUpdateCell.reconcile(BufferCounterUpdateCell.java:67) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.db.filter.QueryFilter$1.reduce(QueryFilter.java:122) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.db.filter.QueryFilter$1.reduce(QueryFilter.java:116) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]        at org.apache.cassandra.utils.MergeIterator$ManyToOne.consume(MergeIterator.java:114) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.utils.MergeIterator$ManyToOne.computeNext(MergeIterator.java:100) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]        at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:143) ~[guava-16.0.1.jar:na]
        at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:138) ~[guava-16.0.1.jar:na]
        at org.apache.cassandra.db.filter.SliceQueryFilter.collectReducedColumns(SliceQueryFilter.java:203) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.db.filter.QueryFilter.collateColumns(QueryFilter.java:108) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.db.filter.QueryFilter.collateOnDiskAtom(QueryFilter.java:82) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.db.filter.QueryFilter.collateOnDiskAtom(QueryFilter.java:69) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.db.CollationController.collectAllData(CollationController.java:314) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.db.CollationController.getTopLevelColumns(CollationController.java:62) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.db.ColumnFamilyStore.getTopLevelColumns(ColumnFamilyStore.java:1900) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.db.ColumnFamilyStore.getColumnFamily(ColumnFamilyStore.java:1758) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.db.Keyspace.getRow(Keyspace.java:346) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.db.SliceFromReadCommand.getRow(SliceFromReadCommand.java:57) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.db.ReadVerbHandler.doVerb(ReadVerbHandler.java:47) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.net.MessageDeliveryTask.run(MessageDeliveryTask.java:62) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) ~[na:1.7.0_80]
        at org.apache.cassandra.concurrent.AbstractTracingAwareExecutorService$FutureTask.run(AbstractTracingAwareExecutorService.java:164) ~[cassandra-all-2.1.5.469.jar:2.1.5.469]
        at org.apache.cassandra.concurrent.SEPWorker.run(SEPWorker.java:105) [cassandra-all-2.1.5.469.jar:2.1.5.469]
        at java.lang.Thread.run(Thread.java:745) [na:1.7.0_80]
ERROR [Thrift-Selector_4] 2015-06-15 18:56:39,677  Message.java:238 - Got an IOException during write!