[infinispan-dev] WriteSkewException: Write skew detected on key

Testing CapeDwarf in a cluster I get WriteSkewException. Any idea what could cause this ? Config issue ? Matej. 15:39:25,171 ERROR [org.infinispan.remoting.InboundInvocationHandlerImpl] (remote-thread-1) Exception executing command: org.infinispan.transaction.WriteSkewException: Write skew detected on key UPDATE(2)/__entity_group__(1) for transaction null at org.infinispan.transaction.WriteSkewHelper.performWriteSkewCheckAndReturnNewVersions(WriteSkewHelper.java:99) at org.infinispan.interceptors.locking.ClusteringDependentLogic$DistributionLogic.createNewVersionsAndCheckForWriteSkews(ClusteringDependentLogic.java:478) at org.infinispan.interceptors.VersionedEntryWrappingInterceptor.visitPrepareCommand(VersionedEntryWrappingInterceptor.java:73) at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:147) at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:120) at org.infinispan.interceptors.locking.AbstractTxLockingInterceptor.invokeNextAndCommitIf1Pc(AbstractTxLockingInterceptor.java:116) at org.infinispan.interceptors.locking.OptimisticLockingInterceptor.visitPrepareCommand(OptimisticLockingInterceptor.java:109) at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:147) at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:120) at org.infinispan.interceptors.NotificationInterceptor.visitPrepareCommand(NotificationInterceptor.java:58) at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:147) at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:120) at org.infinispan.interceptors.TxInterceptor.invokeNextInterceptorAndVerifyTransaction(TxInterceptor.java:130) at org.infinispan.interceptors.TxInterceptor.visitPrepareCommand(TxInterceptor.java:117) at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:147) at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:120) at org.infinispan.interceptors.base.CommandInterceptor.handleDefault(CommandInterceptor.java:134) at org.infinispan.commands.AbstractVisitor.visitPrepareCommand(AbstractVisitor.java:118) at org.infinispan.statetransfer.TransactionSynchronizerInterceptor.visitPrepareCommand(TransactionSynchronizerInterceptor.java:58) at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:147) at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:120) at org.infinispan.statetransfer.StateTransferInterceptor.handleTopologyAffectedCommand(StateTransferInterceptor.java:216) at org.infinispan.statetransfer.StateTransferInterceptor.handleTxCommand(StateTransferInterceptor.java:189) at org.infinispan.statetransfer.StateTransferInterceptor.visitPrepareCommand(StateTransferInterceptor.java:93) at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:147) at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:120) at org.infinispan.interceptors.base.CommandInterceptor.handleDefault(CommandInterceptor.java:134) at org.infinispan.commands.AbstractVisitor.visitPrepareCommand(AbstractVisitor.java:118) at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:147) at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:120) at org.infinispan.interceptors.InvocationContextInterceptor.handleAll(InvocationContextInterceptor.java:128) at org.infinispan.interceptors.InvocationContextInterceptor.handleDefault(InvocationContextInterceptor.java:92) at org.infinispan.commands.AbstractVisitor.visitPrepareCommand(AbstractVisitor.java:118) at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:147) at org.infinispan.interceptors.InterceptorChain.invoke(InterceptorChain.java:343) at org.infinispan.commands.tx.PrepareCommand.perform(PrepareCommand.java:137) at org.infinispan.remoting.InboundInvocationHandlerImpl.handleInternal(InboundInvocationHandlerImpl.java:122) at org.infinispan.remoting.InboundInvocationHandlerImpl.access$000(InboundInvocationHandlerImpl.java:68) at org.infinispan.remoting.InboundInvocationHandlerImpl$2.run(InboundInvocationHandlerImpl.java:194) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_09-icedtea] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_09-icedtea] at java.lang.Thread.run(Thread.java:722) [rt.jar:1.7.0_09-icedtea]