Erro 500 aplicação JSF

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Alguém pode me ajudar com este erro:
HTTP Status 500 - Error calling action method of component with id pesquisaUsuario:botaoConsultar

type Exception report

message Error calling action method of component with id pesquisaUsuario:botaoConsultar

description The server encountered an internal error that prevented it from fulfilling this request.

exception

javax.faces.FacesException: Error calling action method of component with id pesquisaUsuario:botaoConsultar
org.apache.myfaces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:69)
javax.faces.component.UICommand.broadcast(UICommand.java:121)
javax.faces.component.UIViewRoot._broadcastForPhase(UIViewRoot.java:292)
javax.faces.component.UIViewRoot.process(UIViewRoot.java:209)
javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:117)
org.apache.myfaces.lifecycle.InvokeApplicationExecutor.execute(InvokeApplicationExecutor.java:32)
org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:103)
org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:76)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:148)
org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter.doFilterInternal(OpenEntityManagerInViewFilter.java:112)
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:75)
org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:147)
br.gov.dataprev.siprev.seguranca.filter.SecurityFilter.doFilter(SecurityFilter.java:95)
br.gov.dataprev.siprev.seguranca.filter.CredentialsLoaderFilter.doFilter(CredentialsLoaderFilter.java:47)

root cause

javax.faces.el.EvaluationException: javax.el.ELException: /protected/jsps/pesquisa/pesquisaUsuario.xhtml @55,157 action="#{pesquisaUsuarioBean.consultar}": Exception [TOPLINK-6015] (Oracle TopLink Essentials - 2.0 (Build b41-beta2 (03/30/2007))): oracle.toplink.essentials.exceptions.QueryException
Exception Description: Invalid query key [usuario] in expression.
Query: ReportQuery(br.gov.dataprev.siprev.modelo.servidor.Servidor)
javax.faces.component._MethodExpressionToMethodBinding.invoke(_MethodExpressionToMethodBinding.java:79)
org.apache.myfaces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:54)
javax.faces.component.UICommand.broadcast(UICommand.java:121)
javax.faces.component.UIViewRoot._broadcastForPhase(UIViewRoot.java:292)
javax.faces.component.UIViewRoot.process(UIViewRoot.java:209)
javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:117)
org.apache.myfaces.lifecycle.InvokeApplicationExecutor.execute(InvokeApplicationExecutor.java:32)
org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:103)
org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:76)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:148)
org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter.doFilterInternal(OpenEntityManagerInViewFilter.java:112)
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:75)
org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:147)
br.gov.dataprev.siprev.seguranca.filter.SecurityFilter.doFilter(SecurityFilter.java:95)
br.gov.dataprev.siprev.seguranca.filter.CredentialsLoaderFilter.doFilter(CredentialsLoaderFilter.java:47)

root cause

javax.el.ELException: /protected/jsps/pesquisa/pesquisaUsuario.xhtml @55,157 action="#{pesquisaUsuarioBean.consultar}": Exception [TOPLINK-6015] (Oracle TopLink Essentials - 2.0 (Build b41-beta2 (03/30/2007))): oracle.toplink.essentials.exceptions.QueryException
Exception Description: Invalid query key [usuario] in expression.
Query: ReportQuery(br.gov.dataprev.siprev.modelo.servidor.Servidor)
com.sun.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:74)
javax.faces.component._MethodExpressionToMethodBinding.invoke(_MethodExpressionToMethodBinding.java:75)
org.apache.myfaces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:54)
javax.faces.component.UICommand.broadcast(UICommand.java:121)
javax.faces.component.UIViewRoot._broadcastForPhase(UIViewRoot.java:292)
javax.faces.component.UIViewRoot.process(UIViewRoot.java:209)
javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:117)
org.apache.myfaces.lifecycle.InvokeApplicationExecutor.execute(InvokeApplicationExecutor.java:32)
org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:103)
org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:76)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:148)
org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter.doFilterInternal(OpenEntityManagerInViewFilter.java:112)
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:75)
org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:147)
br.gov.dataprev.siprev.seguranca.filter.SecurityFilter.doFilter(SecurityFilter.java:95)
br.gov.dataprev.siprev.seguranca.filter.CredentialsLoaderFilter.doFilter(CredentialsLoaderFilter.java:47)

root cause

Exception [TOPLINK-6015] (Oracle TopLink Essentials - 2.0 (Build b41-beta2 (03/30/2007))): oracle.toplink.essentials.exceptions.QueryException
Exception Description: Invalid query key [usuario] in expression.
Query: ReportQuery(br.gov.dataprev.siprev.modelo.servidor.Servidor)
oracle.toplink.essentials.exceptions.QueryException.invalidQueryKeyInExpression(QueryException.java:609)
oracle.toplink.essentials.internal.expressions.QueryKeyExpression.validateNode(QueryKeyExpression.java:657)
oracle.toplink.essentials.expressions.Expression.normalize(Expression.java:2562)
oracle.toplink.essentials.internal.expressions.DataExpression.normalize(DataExpression.java:343)
oracle.toplink.essentials.internal.expressions.QueryKeyExpression.normalize(QueryKeyExpression.java:440)
oracle.toplink.essentials.internal.expressions.QueryKeyExpression.normalize(QueryKeyExpression.java:427)
oracle.toplink.essentials.internal.expressions.RelationExpression.normalize(RelationExpression.java:496)
oracle.toplink.essentials.internal.expressions.SQLSelectStatement.normalize(SQLSelectStatement.java:1186)
oracle.toplink.essentials.internal.queryframework.ExpressionQueryMechanism.buildReportQuerySelectStatement(ExpressionQueryMechanism.java:467)
oracle.toplink.essentials.internal.queryframework.ExpressionQueryMechanism.buildReportQuerySelectStatement(ExpressionQueryMechanism.java:418)
oracle.toplink.essentials.internal.queryframework.ExpressionQueryMechanism.prepareReportQuerySelectAllRows(ExpressionQueryMechanism.java:1410)
oracle.toplink.essentials.queryframework.ReportQuery.prepareSelectAllRows(ReportQuery.java:1030)
oracle.toplink.essentials.queryframework.ReadAllQuery.prepare(ReadAllQuery.java:398)
oracle.toplink.essentials.queryframework.ReportQuery.prepare(ReportQuery.java:904)
oracle.toplink.essentials.queryframework.DatabaseQuery.checkPrepare(DatabaseQuery.java:387)
oracle.toplink.essentials.queryframework.ObjectLevelReadQuery.checkPrepare(ObjectLevelReadQuery.java:469)
oracle.toplink.essentials.queryframework.DatabaseQuery.execute(DatabaseQuery.java:587)
oracle.toplink.essentials.queryframework.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:677)
oracle.toplink.essentials.queryframework.ObjectLevelReadQuery.executeInUnitOfWork(ObjectLevelReadQuery.java:731)
oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2219)
oracle.toplink.essentials.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:937)
oracle.toplink.essentials.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:909)
oracle.toplink.essentials.internal.ejb.cmp3.base.EJBQueryImpl.executeReadQuery(EJBQueryImpl.java:346)
oracle.toplink.essentials.internal.ejb.cmp3.base.EJBQueryImpl.getResultList(EJBQueryImpl.java:453)
org.springframework.orm.jpa.JpaTemplate$10.doInJpa(JpaTemplate.java:330)
org.springframework.orm.jpa.JpaTemplate.execute(JpaTemplate.java:184)
org.springframework.orm.jpa.JpaTemplate.executeFind(JpaTemplate.java:151)
org.springframework.orm.jpa.JpaTemplate.findByNamedParams(JpaTemplate.java:322)
br.gov.dataprev.siprev.persistencia.servidor.ServidorDAOImpl.findByUsuario(ServidorDAOImpl.java:533)
br.gov.dataprev.siprev.negocio.usuario.UsuarioServidorBOImpl.findByUsuario(UsuarioServidorBOImpl.java:154)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:310)
org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
org.springframework.aop.framework.adapter.MethodBeforeAdviceInterceptor.invoke(MethodBeforeAdviceInterceptor.java:50)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
com.sun.proxy.$Proxy67.findByUsuario(Unknown Source)
br.gov.dataprev.siprev.mbean.cadastro.PesquisaUsuarioBean.atualizaUsuarios(PesquisaUsuarioBean.java:207)
br.gov.dataprev.siprev.mbean.cadastro.PesquisaUsuarioBean.consultar(PesquisaUsuarioBean.java:229)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
org.apache.el.parser.AstValue.invoke(AstValue.java:278)
org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:274)
com.sun.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:68)
javax.faces.component._MethodExpressionToMethodBinding.invoke(_MethodExpressionToMethodBinding.java:75)
org.apache.myfaces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:54)
javax.faces.component.UICommand.broadcast(UICommand.java:121)
javax.faces.component.UIViewRoot._broadcastForPhase(UIViewRoot.java:292)
javax.faces.component.UIViewRoot.process(UIViewRoot.java:209)
javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:117)
org.apache.myfaces.lifecycle.InvokeApplicationExecutor.execute(InvokeApplicationExecutor.java:32)
org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:103)
org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:76)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:148)
org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter.doFilterInternal(OpenEntityManagerInViewFilter.java:112)
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:75)
org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:147)
br.gov.dataprev.siprev.seguranca.filter.SecurityFilter.doFilter(SecurityFilter.java:95)
br.gov.dataprev.siprev.seguranca.filter.CredentialsLoaderFilter.doFilter(CredentialsLoaderFilter.java:47)

note The full stack trace of the root cause is available in the Apache Tomcat/7.0.47 logs.
Apache Tomcat/7.0.47

Desde já agradeço.