See linked bugzilla.

This issue is for the scenario of "old" 5.2.4.Final cluster being migrated to 6.0.0 and this causes protocol mismatch error.

Caused by: org.infinispan.commons.CacheException: Unable to start cache loaders
at org.infinispan.persistence.manager.PersistenceManagerImpl.start(PersistenceManagerImpl.java:155)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.7.0_02]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) [rt.jar:1.7.0_02]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.7.0_02]
at java.lang.reflect.Method.invoke(Method.java:601) [rt.jar:1.7.0_02]
at org.infinispan.commons.util.ReflectionUtil.invokeAccessibly(ReflectionUtil.java:183)
... 18 more
Caused by: org.infinispan.client.hotrod.exceptions.HotRodClientException:Request for message id[2] returned server error (status=0x85): scala.MatchError: 13 (of class java.lang.Byte)
at org.infinispan.client.hotrod.impl.protocol.Codec10.checkForErrorsInResponseStatus(Codec10.java:143)
at org.infinispan.client.hotrod.impl.protocol.Codec10.readHeader(Codec10.java:99)
at org.infinispan.client.hotrod.impl.operations.HotRodOperation.readHeaderAndValidate(HotRodOperation.java:56)
at org.infinispan.client.hotrod.impl.operations.PingOperation.execute(PingOperation.java:44)
at org.infinispan.client.hotrod.impl.operations.FaultTolerantPingOperation.executeOperation(FaultTolerantPingOperation.java:30) at org.infinispan.client.hotrod.impl.operations.FaultTolerantPingOperation.executeOperation(FaultTolerantPingOperation.java:16) at org.infinispan.client.hotrod.impl.operations.RetryOnFailureOperation.execute(RetryOnFailureOperation.java:46)
at org.infinispan.client.hotrod.impl.RemoteCacheImpl.ping(RemoteCacheImpl.java:433)
at org.infinispan.client.hotrod.RemoteCacheManager.ping(RemoteCacheManager.java:632)
at org.infinispan.client.hotrod.RemoteCacheManager.createRemoteCache(RemoteCacheManager.java:613)
at org.infinispan.client.hotrod.RemoteCacheManager.getCache(RemoteCacheManager.java:524)
at org.infinispan.client.hotrod.RemoteCacheManager.getCache(RemoteCacheManager.java:520)
at org.infinispan.persistence.remote.RemoteStore.start(RemoteStore.java:89)
at org.infinispan.persistence.manager.PersistenceManagerImpl.start(PersistenceManagerImpl.java:122)
... 23 more