From time to time I got the following exception message on GAE for my GAE/J app. I searched with Google, no relevant results were found. Does anyone know about this? Thanks in advance for any response!

The exception message is as below:

Nested in org.springframework.orm.jpa.JpaSystemException: Illegal argument; nested exception is javax.persistence.PersistenceException: Illegal argument: java.lang.IllegalArgumentException: read operations inside transactions can't allow failover at com.google.appengine.api.datastore.DatastoreApiHelper.translateError(DatastoreApiHelper.java: 34) at com.google.appengine.api.datastore.DatastoreApiHelper.makeSyncCall(DatastoreApiHelper.java: 67) at com.google.appengine.api.datastore.DatastoreServiceImpl $1.run(DatastoreServiceImpl.java:128) at com.google.appengine.api.datastore.TransactionRunner.runInTransaction(TransactionRunner.java: 30) at com.google.appengine.api.datastore.DatastoreServiceImpl.get(DatastoreServiceImpl.java: 111) at com.google.appengine.api.datastore.DatastoreServiceImpl.get(DatastoreServiceImpl.java: 84) at com.google.appengine.api.datastore.DatastoreServiceImpl.get(DatastoreServiceImpl.java: 77) at org.datanucleus.store.appengine.RuntimeExceptionWrappingDatastoreService.get(RuntimeExceptionWrappingDatastoreService.java: 53) at org.datanucleus.store.appengine.DatastorePersistenceHandler.get(DatastorePersistenceHandler.java: 94) at org.datanucleus.store.appengine.DatastorePersistenceHandler.get(DatastorePersistenceHandler.java: 106) at org.datanucleus.store.appengine.DatastorePersistenceHandler.fetchObject(DatastorePersistenceHandler.java: 464) at org.datanucleus.state.JDOStateManagerImpl.loadUnloadedFieldsInFetchPlan(JDOStateManagerImpl.java: 1627) at org.datanucleus.state.JDOStateManagerImpl.loadFieldsInFetchPlan(JDOStateManagerImpl.java: 1603) at org.datanucleus.ObjectManagerImpl.performDetachAllOnCommitPreparation(ObjectManagerImpl.java: 3192) at org.datanucleus.ObjectManagerImpl.preCommit(ObjectManagerImpl.java: 2931) at org.datanucleus.TransactionImpl.internalPreCommit(TransactionImpl.java: 369) at org.datanucleus.TransactionImpl.commit(TransactionImpl.java:256) at org.datanucleus.jpa.EntityTransactionImpl.commit(EntityTransactionImpl.java: 104) at org.datanucleus.store.appengine.jpa.DatastoreEntityTransactionImpl.commit(DatastoreEntityTransactionImpl.java: 55) at name.kenyth.playtweets.service.Tx.run(Tx.java:39) at name.kenyth.playtweets.web.controller.TwitterApiController.persistStatus(TwitterApiController.java: 309) at name.kenyth.playtweets.web.controller.TwitterApiController.processStatusesForWebCall(TwitterApiController.java: 271) at name.kenyth.playtweets.web.controller.TwitterApiController.getHomeTimelineUpdates_aroundBody0(TwitterApiController.java: 247) at name.kenyth.playtweets.web.controller.TwitterApiController $AjcClosure1.run(TwitterApiController.java:1) at name.kenyth.playtweets.web.refine.AuthenticationEnforcement.ajc $around$name_kenyth_playtweets_web_refine_AuthenticationEnforcement $2$439820b7proceed(AuthenticationEnforcement.aj:1) at name.kenyth.playtweets.web.refine.AuthenticationEnforcement.ajc $around$name_kenyth_playtweets_web_refine_AuthenticationEnforcement $2$439820b7(AuthenticationEnforcement.aj:168) at name.kenyth.playtweets.web.controller.TwitterApiController.getHomeTimelineUpdates(TwitterApiController.java: 129) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Method.java:43) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.doInvokeMethod(HandlerMethodInvoker.java: 710) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java: 167) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java: 414) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java: 402) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java: 771) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java: 716) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java: 647) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java: 552) at javax.servlet.http.HttpServlet.service(HttpServlet.java:693) at javax.servlet.http.HttpServlet.service(HttpServlet.java:806) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java: 511) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java: 390) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java: 216) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java: 182) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java: 765) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java: 418) at org.mortbay.jetty.servlet.Dispatcher.forward(Dispatcher.java:327) at org.mortbay.jetty.servlet.Dispatcher.forward(Dispatcher.java:126) at org.tuckey.web.filters.urlrewrite.NormalRewrittenUrl.doRewrite(NormalRewrittenUrl.java: 195) at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java: 159) at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java: 141) at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java: 90) at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java: 417) at org.mortbay.jetty.servlet.ServletHandler $CachedChain.doFilter(ServletHandler.java:1157) at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java: 71) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java: 76) at org.mortbay.jetty.servlet.ServletHandler $CachedChain.doFilter(ServletHandler.java:1157) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java: 88) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java: 76) at org.mortbay.jetty.servlet.ServletHandler $CachedChain.doFilter(ServletHandler.java:1157) at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java: 97) at org.mortbay.jetty.servlet.ServletHandler $CachedChain.doFilter(ServletHandler.java:1157) at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java: 35) at org.mortbay.jetty.servlet.ServletHandler $CachedChain.doFilter(ServletHandler.java:1157) at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java: 43) at org.mortbay.jetty.servlet.ServletHandler $CachedChain.doFilter(ServletHandler.java:1157) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java: 388) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java: 216) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java: 182) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java: 765) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java: 418) at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java: 238) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java: 152) at org.mortbay.jetty.Server.handle(Server.java:326) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java: 542) at org.mortbay.jetty.HttpConnection $RequestHandler.headerComplete(HttpConnection.java:923) at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java: 76) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java: 135) at com.google.apphosting.runtime.JavaRuntime.handleRequest(JavaRuntime.java: 250) at com.google.apphosting.base.RuntimePb$EvaluationRuntime $6.handleBlockingRequest(RuntimePb.java:5838) at com.google.apphosting.base.RuntimePb$EvaluationRuntime $6.handleBlockingRequest(RuntimePb.java:5836) at com.google.net.rpc.impl.BlockingApplicationHandler.handleRequest(BlockingApplicationHandler.java: 24) at com.google.net.rpc.impl.RpcUtil.runRpcInApplication