org.hibernate.MappingException: Unknown entity:

Hi Guys ,

org.hibernate.MappingException: Unknown entity:  is a common error you may face while runtime .
I have faced this error while a bean call . A session bean of type entity . This can come due to several reasons based on your project .Some of them are as below:
1.In your persistence.xml you need to dd that particular class like as below :
            <class>model.Account</class>

If it is not set you might face the following exception .
01:09:51,133 ERROR [org.jboss.as.ejb3.invocation] (http-localhost/127.0.0.1:8088-2) JBAS014134: EJB Invocation failed on component AccountBean for method public abstract model.Account org.project.banking.AccountRemote.findAccount(model.Account): javax.ejb.EJBException: java.lang.IllegalArgumentException: Unknown entity: model.Account
at org.jboss.as.ejb3.tx.CMTTxInterceptor.handleExceptionInOurTx(CMTTxInterceptor.java:189) [jboss-as-ejb3-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.as.ejb3.tx.CMTTxInterceptor.invokeInOurTx(CMTTxInterceptor.java:274) [jboss-as-ejb3-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.as.ejb3.tx.CMTTxInterceptor.required(CMTTxInterceptor.java:339) [jboss-as-ejb3-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.as.ejb3.tx.CMTTxInterceptor.processInvocation(CMTTxInterceptor.java:238) [jboss-as-ejb3-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ejb3.remote.EJBRemoteTransactionPropagatingInterceptor.processInvocation(EJBRemoteTransactionPropagatingInterceptor.java:79) [jboss-as-ejb3-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ejb3.component.interceptors.CurrentInvocationContextInterceptor.processInvocation(CurrentInvocationContextInterceptor.java:41) [jboss-as-ejb3-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ejb3.component.interceptors.ShutDownInterceptorFactory$1.processInvocation(ShutDownInterceptorFactory.java:64) [jboss-as-ejb3-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ejb3.component.interceptors.LoggingInterceptor.processInvocation(LoggingInterceptor.java:59) [jboss-as-ejb3-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ee.component.NamespaceContextInterceptor.processInvocation(NamespaceContextInterceptor.java:50) [jboss-as-ee-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ejb3.component.interceptors.AdditionalSetupInterceptor.processInvocation(AdditionalSetupInterceptor.java:55) [jboss-as-ejb3-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ee.component.TCCLInterceptor.processInvocation(TCCLInterceptor.java:45) [jboss-as-ee-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ee.component.ViewService$View.invoke(ViewService.java:165) [jboss-as-ee-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.as.ejb3.remote.LocalEjbReceiver.processInvocation(LocalEjbReceiver.java:249) [jboss-as-ejb3-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.ejb.client.EJBClientInvocationContext.sendRequest(EJBClientInvocationContext.java:181) [jboss-ejb-client-1.0.24.Final-redhat-1.jar:1.0.24.Final-redhat-1]
at org.jboss.ejb.client.EJBObjectInterceptor.handleInvocation(EJBObjectInterceptor.java:58) [jboss-ejb-client-1.0.24.Final-redhat-1.jar:1.0.24.Final-redhat-1]
at org.jboss.ejb.client.EJBClientInvocationContext.sendRequest(EJBClientInvocationContext.java:183) [jboss-ejb-client-1.0.24.Final-redhat-1.jar:1.0.24.Final-redhat-1]
at org.jboss.ejb.client.EJBHomeInterceptor.handleInvocation(EJBHomeInterceptor.java:83) [jboss-ejb-client-1.0.24.Final-redhat-1.jar:1.0.24.Final-redhat-1]
at org.jboss.ejb.client.EJBClientInvocationContext.sendRequest(EJBClientInvocationContext.java:183) [jboss-ejb-client-1.0.24.Final-redhat-1.jar:1.0.24.Final-redhat-1]
at org.jboss.ejb.client.TransactionInterceptor.handleInvocation(TransactionInterceptor.java:42) [jboss-ejb-client-1.0.24.Final-redhat-1.jar:1.0.24.Final-redhat-1]
at org.jboss.ejb.client.EJBClientInvocationContext.sendRequest(EJBClientInvocationContext.java:183) [jboss-ejb-client-1.0.24.Final-redhat-1.jar:1.0.24.Final-redhat-1]
at org.jboss.ejb.client.ReceiverInterceptor.handleInvocation(ReceiverInterceptor.java:125) [jboss-ejb-client-1.0.24.Final-redhat-1.jar:1.0.24.Final-redhat-1]
at org.jboss.ejb.client.EJBClientInvocationContext.sendRequest(EJBClientInvocationContext.java:183) [jboss-ejb-client-1.0.24.Final-redhat-1.jar:1.0.24.Final-redhat-1]
at org.jboss.ejb.client.EJBInvocationHandler.sendRequestWithPossibleRetries(EJBInvocationHandler.java:253) [jboss-ejb-client-1.0.24.Final-redhat-1.jar:1.0.24.Final-redhat-1]
at org.jboss.ejb.client.EJBInvocationHandler.doInvoke(EJBInvocationHandler.java:198) [jboss-ejb-client-1.0.24.Final-redhat-1.jar:1.0.24.Final-redhat-1]
at org.jboss.ejb.client.EJBInvocationHandler.doInvoke(EJBInvocationHandler.java:181) [jboss-ejb-client-1.0.24.Final-redhat-1.jar:1.0.24.Final-redhat-1]
at org.jboss.ejb.client.EJBInvocationHandler.invoke(EJBInvocationHandler.java:144) [jboss-ejb-client-1.0.24.Final-redhat-1.jar:1.0.24.Final-redhat-1]
at com.sun.proxy.$Proxy25.findAccount(Unknown Source)
at org.project.banking.Banking.getAllAccounts(Banking.java:32) [ConsultingJava.jar:]
at org.project.banking.Banking.processRequest(Banking.java:45) [ConsultingJava.jar:]
at org.project.common.router.CommonRouter.commonRoute(CommonRouter.java:63) [ConsultingJava.jar:]
at org.project.common.router.CommonRouter.route(CommonRouter.java:21) [ConsultingJava.jar:]
at org.project.common.web.CommonController.doPost(CommonController.java:69) [ConsultingJava.jar:]
at org.project.common.web.CommonController.doGet(CommonController.java:51) [ConsultingJava.jar:]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:734) [jboss-servlet-api_3.0_spec-1.0.2.Final-redhat-1.jar:1.0.2.Final-redhat-1]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [jboss-servlet-api_3.0_spec-1.0.2.Final-redhat-1.jar:1.0.2.Final-redhat-1]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:295)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:149)
at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50) [jboss-as-jpa-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50) [jboss-as-jpa-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:169)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:145)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:97)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:102)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:336)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:653)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:920)
at java.lang.Thread.run(Unknown Source) [rt.jar:1.7.0_51]
Caused by: java.lang.IllegalArgumentException: Unknown entity: model.Account
at org.hibernate.ejb.AbstractEntityManagerImpl.find(AbstractEntityManagerImpl.java:829) [hibernate-entitymanager-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
at org.hibernate.ejb.AbstractEntityManagerImpl.find(AbstractEntityManagerImpl.java:781) [hibernate-entitymanager-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
at org.jboss.as.jpa.container.AbstractEntityManager.find(AbstractEntityManager.java:193) [jboss-as-jpa-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.project.banking.AccountBean.findAccount(AccountBean.java:42) [Bean2.jar:]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.7.0_51]
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) [rt.jar:1.7.0_51]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) [rt.jar:1.7.0_51]
at java.lang.reflect.Method.invoke(Unknown Source) [rt.jar:1.7.0_51]
at org.jboss.as.ee.component.ManagedReferenceMethodInterceptorFactory$ManagedReferenceMethodInterceptor.processInvocation(ManagedReferenceMethodInterceptorFactory.java:72) [jboss-as-ee-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.invocation.WeavedInterceptor.processInvocation(WeavedInterceptor.java:53) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ee.component.interceptors.UserInterceptorFactory$1.processInvocation(UserInterceptorFactory.java:58) [jboss-as-ee-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.invocation.WeavedInterceptor.processInvocation(WeavedInterceptor.java:53) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ee.component.interceptors.UserInterceptorFactory$1.processInvocation(UserInterceptorFactory.java:58) [jboss-as-ee-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ejb3.component.invocationmetrics.ExecutionTimeInterceptor.processInvocation(ExecutionTimeInterceptor.java:43) [jboss-as-ejb3-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.jpa.interceptor.SBInvocationInterceptor.processInvocation(SBInvocationInterceptor.java:47) [jboss-as-jpa-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.invocation.InitialInterceptor.processInvocation(InitialInterceptor.java:21) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ee.component.interceptors.ComponentDispatcherInterceptor.processInvocation(ComponentDispatcherInterceptor.java:53) [jboss-as-ee-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ejb3.component.pool.PooledInstanceInterceptor.processInvocation(PooledInstanceInterceptor.java:51) [jboss-as-ejb3-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.2.Final-redhat-1.jar:1.1.2.Final-redhat-1]
at org.jboss.as.ejb3.tx.CMTTxInterceptor.invokeInOurTx(CMTTxInterceptor.java:272) [jboss-as-ejb3-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]

... 57 more

at org.hibernate.internal.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:1143) [hibernate-core-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
at org.hibernate.internal.SessionImpl.locateEntityPersister(SessionImpl.java:2493) [hibernate-core-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
at org.hibernate.internal.SessionImpl.access$1900(SessionImpl.java:175) [hibernate-core-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.<init>(SessionImpl.java:2435) [hibernate-core-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.<init>(SessionImpl.java:2439) [hibernate-core-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.<init>(SessionImpl.java:2426) [hibernate-core-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
at org.hibernate.internal.SessionImpl.byId(SessionImpl.java:1071) [hibernate-core-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
at org.hibernate.internal.SessionImpl.get(SessionImpl.java:994) [hibernate-core-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
at org.hibernate.ejb.AbstractEntityManagerImpl.find(AbstractEntityManagerImpl.java:807) [hibernate-entitymanager-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
... 84 more