検索すると一部のクライアント端末だけシステムエラーが発生する。

(from osdn.net/users/katsu2015)
いつもお世話になっております。

検索を実行すると、一部のクライアント端末だけ以下のシステムエラーが発生します。
ブラウザは、システムエラーが発生するクライアント端末、発生しないクライアント端末ともに同じIE11です。

以下はfess.outの内容です。
以下のエラーが発生する理由を教えてください。

2015-10-26 15:34:40,316 [ajp-apr-18009-exec-4] ERROR System error occured.
org.seasar.dbflute.exception.EntityDuplicatedException: Look! Read the message below.
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
The selected entity was duplicated! It should be the only one.

[Advice]
Confirm your search condition. Does it really select the only one?
And confirm your database. Does it really exist the only one?
For example:
(x):
cb.query().setMemberName_PrefisSearch(“S”);
… = memberBhv.selectEntity(cb);
(o):
cb.query().setMemberId_Equal(3);
… = memberBhv.selectEntity(cb);

[Result Count]
{over safetyMaxResultSize ‘1’}
[Display SQL]
select dfloc.ID as ID, dfloc.CODE as CODE, dfloc.CREATED_TIME as CREATED_TIME, dfloc.UPDATED_TIME as UPDATED_TIME
from USER_INFO dfloc
where dfloc.CODE = ‘××××××××××’ ←×の部分はセキュリティのためマスクします。

                  • */
                    at org.seasar.dbflute.exception.thrower.BehaviorExceptionThrower.throwSelectEntityDuplicatedException(BehaviorExceptionThrower.java:83)
                    at org.seasar.dbflute.bhv.AbstractBehaviorReadable.throwSelectEntityDuplicatedException(AbstractBehaviorReadable.java:284)
                    at org.seasar.dbflute.bhv.AbstractBehaviorReadable.helpSelectEntityInternally(AbstractBehaviorReadable.java:207)
                    at org.seasar.dbflute.bhv.AbstractBehaviorReadable.doSelectEntity(AbstractBehaviorReadable.java:181)
                    at jp.sf.fess.db.bsbhv.BsUserInfoBhv.facadeSelectEntity(BsUserInfoBhv.java:176)
                    at jp.sf.fess.db.bsbhv.BsUserInfoBhv.selectEntity(BsUserInfoBhv.java:172)
                    at jp.sf.fess.service.UserInfoService.getUserInfo(UserInfoService.java:100)
                    at jp.sf.fess.service.UserInfoService$$EnhancedByS2AOP$$5efd372d.$$getUserInfo$$invokeSuperMethod$$(UserInfoService$$EnhancedByS2AOP$$5efd372d.java)
                    at jp.sf.fess.service.UserInfoService$$EnhancedByS2AOP$$5efd372d$$MethodInvocation$$getUserInfo0.proceed(MethodInvocationClassGenerator.java)
                    at org.seasar.extension.tx.DefaultTransactionCallback.execute(DefaultTransactionCallback.java:58)
                    at org.seasar.extension.tx.adapter.JTATransactionManagerAdapter.required(JTATransactionManagerAdapter.java:65)
                    at org.seasar.extension.tx.RequiredInterceptor.invoke(RequiredInterceptor.java:50)
                    at jp.sf.fess.service.UserInfoService$$EnhancedByS2AOP$$5efd372d$$MethodInvocation$$getUserInfo0.proceed(MethodInvocationClassGenerator.java)
                    at org.seasar.framework.aop.interceptors.TraceInterceptor.invoke(TraceInterceptor.java:56)
                    at jp.sf.fess.service.UserInfoService$$EnhancedByS2AOP$$5efd372d$$MethodInvocation$$getUserInfo0.proceed(MethodInvocationClassGenerator.java)
                    at jp.sf.fess.service.UserInfoService$$EnhancedByS2AOP$$5efd372d.getUserInfo(UserInfoService$$EnhancedByS2AOP$$5efd372d.java)
                    at jp.sf.fess.helper.impl.SearchLogHelperImpl.updateUserInfo(SearchLogHelperImpl.java:60)
                    at jp.sf.fess.helper.impl.CookieUserInfoHelperImpl.updateUserSessionId(CookieUserInfoHelperImpl.java:89)
                    at jp.sf.fess.helper.impl.CookieUserInfoHelperImpl.getUserCode(CookieUserInfoHelperImpl.java:79)
                    at jp.sf.fess.action.IndexAction.doSearchInternal(IndexAction.java:1107)
                    at jp.sf.fess.action.IndexAction.doSearch(IndexAction.java:349)
                    at jp.sf.fess.action.IndexAction.search(IndexAction.java:517)
                    at jp.sf.fess.action.IndexAction$$EnhancedByS2AOP$$2a1f139f.$$search$$invokeSuperMethod$$(IndexAction$$EnhancedByS2AOP$$2a1f139f.java)
                    at jp.sf.fess.action.IndexAction$$EnhancedByS2AOP$$2a1f139f$$MethodInvocation$$search5.proceed(MethodInvocationClassGenerator.java)
                    at org.codelibs.sastruts.core.interceptor.TokenInterceptor.invoke(TokenInterceptor.java:60)
                    at jp.sf.fess.action.IndexAction$$EnhancedByS2AOP$$2a1f139f$$MethodInvocation$$search5.proceed(MethodInvocationClassGenerator.java)
                    at org.seasar.framework.aop.interceptors.ThrowsInterceptor.invoke(ThrowsInterceptor.java:79)
                    at jp.sf.fess.interceptor.FessActionMessagesThrowsInterceptor.invoke(FessActionMessagesThrowsInterceptor.java:38)
                    at jp.sf.fess.action.IndexAction$$EnhancedByS2AOP$$2a1f139f$$MethodInvocation$$search5.proceed(MethodInvocationClassGenerator.java)
                    at org.seasar.framework.aop.interceptors.TraceInterceptor.invoke(TraceInterceptor.java:56)
                    at jp.sf.fess.action.IndexAction$$EnhancedByS2AOP$$2a1f139f$$MethodInvocation$$search5.proceed(MethodInvocationClassGenerator.java)
                    at jp.sf.fess.action.IndexAction$$EnhancedByS2AOP$$2a1f139f.search(IndexAction$$EnhancedByS2AOP$$2a1f139f.java)
                    at sun.reflect.GeneratedMethodAccessor497.invoke(Unknown Source)
                    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
                    at java.lang.reflect.Method.invoke(Method.java:606)
                    at org.seasar.framework.util.MethodUtil.invoke(MethodUtil.java:96)
                    at org.seasar.struts.action.ActionWrapper.execute(ActionWrapper.java:139)
                    at org.seasar.struts.action.ActionWrapper.execute(ActionWrapper.java:87)
                    at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
                    at org.seasar.struts.action.S2RequestProcessor.process(S2RequestProcessor.java:132)
                    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1216)
                    at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:434)
                    at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
                    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
                    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
                    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
                    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
                    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
                    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
                    at jp.co.mms.fess.customize.filter.MmsLoginFilter.doFilter(MmsLoginFilter.java:82)
                    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
                    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
                    at org.seasar.framework.container.hotdeploy.HotdeployFilter.doFilter(HotdeployFilter.java:71)
                    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
                    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
                    at org.seasar.framework.container.filter.S2ContainerFilter.doFilter(S2ContainerFilter.java:79)
                    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
                    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
                    at org.seasar.extension.filter.EncodingFilter.doFilter(EncodingFilter.java:69)
                    at jp.sf.fess.filter.FessEncodingFilter.doFilter(FessEncodingFilter.java:124)
                    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
                    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
                    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:721)
                    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:466)
                    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:391)
                    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:318)
                    at org.seasar.struts.filter.RoutingFilter.forward(RoutingFilter.java:219)
                    at org.seasar.struts.filter.RoutingFilter.doFilter(RoutingFilter.java:130)
                    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
                    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
                    at jp.sf.fess.filter.WebApiFilter.doFilter(WebApiFilter.java:55)
                    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
                    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
                    at org.codelibs.sastruts.core.filter.AuthFilter.doFilter(AuthFilter.java:161)
                    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
                    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
                    at org.seasar.framework.container.hotdeploy.HotdeployFilter.doFilter(HotdeployFilter.java:71)
                    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
                    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
                    at org.seasar.framework.container.filter.S2ContainerFilter.doFilter(S2ContainerFilter.java:79)
                    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
                    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
                    at org.seasar.extension.filter.EncodingFilter.doFilter(EncodingFilter.java:69)
                    at jp.sf.fess.filter.FessEncodingFilter.doFilter(FessEncodingFilter.java:124)
                    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
                    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
                    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
                    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
                    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
                    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
                    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
                    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
                    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
                    at org.apache.coyote.ajp.AbstractAjpProcessor.process(AbstractAjpProcessor.java:844)
                    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668)
                    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2463)
                    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2452)
                    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
                    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
                    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
                    at java.lang.Thread.run(Thread.java:745)
                    Caused by: org.seasar.dbflute.exception.FetchingOverSafetySizeException: The fetching was over the specified safety size: 1
                    at org.seasar.dbflute.s2dao.jdbc.TnFetchAssistResultSet.throwFetchingOverSafetySizeException(TnFetchAssistResultSet.java:217)
                    at org.seasar.dbflute.s2dao.jdbc.TnFetchAssistResultSet.checkSafetyResult(TnFetchAssistResultSet.java:210)
                    at org.seasar.dbflute.s2dao.jdbc.TnFetchAssistResultSet.next(TnFetchAssistResultSet.java:177)
                    at org.seasar.dbflute.s2dao.rshandler.TnBeanListResultSetHandler.mappingBean(TnBeanListResultSetHandler.java:98)
                    at org.seasar.dbflute.s2dao.rshandler.TnBeanListResultSetHandler.handle(TnBeanListResultSetHandler.java:61)
                    at org.seasar.dbflute.s2dao.sqlhandler.TnBasicSelectHandler.queryResult(TnBasicSelectHandler.java:87)
                    at org.seasar.dbflute.s2dao.sqlhandler.TnBasicSelectHandler.doExecute(TnBasicSelectHandler.java:72)
                    at org.seasar.dbflute.s2dao.sqlhandler.TnBasicParameterHandler.execute(TnBasicParameterHandler.java:46)
                    at org.seasar.dbflute.s2dao.sqlcommand.TnAbstractTwoWaySqlCommand.execute(TnAbstractTwoWaySqlCommand.java:57)
                    at org.seasar.dbflute.bhv.core.execution.SelectCBExecution.superExecute(SelectCBExecution.java:84)
                    at org.seasar.dbflute.bhv.core.execution.SelectCBExecution.execute(SelectCBExecution.java:80)
                    at org.seasar.dbflute.bhv.core.BehaviorCommandInvoker.executeSql(BehaviorCommandInvoker.java:418)
                    at org.seasar.dbflute.bhv.core.BehaviorCommandInvoker.dispatchInvoking(BehaviorCommandInvoker.java:237)
                    at org.seasar.dbflute.bhv.core.BehaviorCommandInvoker.invoke(BehaviorCommandInvoker.java:163)
                    at org.seasar.dbflute.bhv.AbstractBehaviorReadable.invoke(AbstractBehaviorReadable.java:1575)
                    at org.seasar.dbflute.bhv.AbstractBehaviorReadable.delegateSelectList(AbstractBehaviorReadable.java:1400)
                    at org.seasar.dbflute.bhv.AbstractBehaviorReadable.helpSelectEntityInternally(AbstractBehaviorReadable.java:205)
                    … 98 more

(from osdn.net/users/shinsuke)
なぜ重複登録されているかは別なログかもしれませんが、管理画面の利用者一覧から対象のコードの利用者情報を削除していただければ、改善されると思います。

(from osdn.net/users/katsu2015)
ご教授の通り、該当の利用者IDを削除したら、システムエラーが発生しなくなりました。ありがとうございました。

ちなみに、該当の利用者IDで本件のログより以前のログを確認すると、以下の記録がありました。

2015-09-28 09:49:00,040 [JobScheduler_Worker-3] WARN Failed to process: ClickLog [queryRequestedTime=2015-09-28 09:47:18.437, userSessionId=xxxxxxxxxxx, docId=d3bd50c5c5b3444d81e2d520b9cec483, clickCount=0, _id=null, _searchId=null, _url=http:/xxxxxxx/WWW/, _requestedTime=2015-09-28 09:48:49.885]
org.seasar.dbflute.exception.EntityDuplicatedException: Look! Read the message below.

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
The selected entity was duplicated! It should be the only one.