Hi , I searched the Seam forum for this problem but did not find exactly this case . I get the following exception navigating my web app that includes a dropdown list . I can go the the page with the dropdown list and save to the database but when I go to the next page and try to return to the dropdown I get the null pointer exception (sometimes) . Not sure how to proceed??? I really like Seam and would like to fix this problem .

java.lang.NullPointerException
 at com.sun.faces.renderkit.html_basic.MenuRenderer.renderOption(MenuRenderer.java:580)
 at com.sun.faces.renderkit.html_basic.MenuRenderer.renderOptions(MenuRenderer.java:757)
 at com.sun.faces.renderkit.html_basic.MenuRenderer.renderSelect(MenuRenderer.java:811)
 at com.sun.faces.renderkit.html_basic.MenuRenderer.encodeEnd(MenuRenderer.java:335)
 at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:833)
 at javax.faces.component.UIComponent.encodeAll(UIComponent.java:896)
 at javax.faces.render.Renderer.encodeChildren(Renderer.java:137)
 at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:809)
 at javax.faces.component.UIComponent.encodeAll(UIComponent.java:886)
 at javax.faces.component.UIComponent.encodeAll(UIComponent.java:892)
 at com.sun.facelets.FaceletViewHandler.renderView(FaceletViewHandler.java:577)
 at org.ajax4jsf.framework.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:108)
 at org.ajax4jsf.framework.ajax.AjaxViewHandler.renderView(AjaxViewHandler.java:233)
 at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:106)
 at com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:251)
 at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:144)
 at javax.faces.webapp.FacesServlet.service(FacesServlet.java:245)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83)
 at org.jboss.seam.debug.hot.HotDeployFilter.doFilter(HotDeployFilter.java:63)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
 at org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:87)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
 at org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:63)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
 at org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:46)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
 at org.ajax4jsf.framework.ajax.xmlfilter.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:127)
 at org.ajax4jsf.framework.ajax.xmlfilter.BaseFilter.doFilter(BaseFilter.java:277)
 at org.jboss.seam.web.Ajax4jsfFilter.doFilter(Ajax4jsfFilter.java:40)
 at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
 at org.jboss.seam.servlet.SeamFilter.doFilter(SeamFilter.java:140)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
 at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179)
 at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433)
 at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
 at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:156)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:241)
 at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
 at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:580)
 at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
 at java.lang.Thread.run(Thread.java:595)

<h:form id="orgProfile1">
 <h1>Register Organization Profile</h1>
 <hr/>
 <h:outputLabel for="orgType" value="#{messages.orgType}"/>
 <h:selectOneMenu value="#{organization.type}" id="orgType">
 <s:selectItems value="#{orgTypeList}" var="type" label="#{type.type}" noSelectionLabel="Select your type"/>
 <s:convertEntity/>
 </h:selectOneMenu>
 <h:commandButton type="submit" value="Save" action="#{profile.save}"/>
 </h:form>

package ca.gc.acdi_cida;

import ....

@Stateful
@Name("profile")
public class OrganizationalProfileAction implements OrganizationalProfile {

 @In (required=false)
 @Out (required=false)
 private Organization organization ;

 @Out (required=false)
 private List<OrganizationalType> orgTypeList;

 @In(create=true)
 private EntityManager entityManager;


 @Begin(join=true)
 @SuppressWarnings("unchecked")
 @Factory( "orgTypeList" )
 public void findOrgTypes() {
 System.out.println( " -------------------- Retrieving types..." );
 orgTypeList = entityManager.createQuery("from OrganizationalType ").getResultList();
 System.out.println(" ------------------ orgTypeList size : "+ orgTypeList.size());

 }

 @End
 public String save(){
 entityManager.persist(organization);
 organization = new Organization();
 return null;
 }

 @Remove @Destroy
 public void destroy() {}

}

package ca.gc.acdi_cida;

import java.io.Serializable;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToOne;

import org.jboss.seam.annotations.Name;

@Entity
@Name("organization")

public class Organization implements Serializable {


 private static final long serialVersionUID = 1L;


 private Integer id;
 private OrganizationalType type;

 public Organization(OrganizationalType type) {
 this.type = type;
 }

 public Organization() {}

 @Id @GeneratedValue
 public Integer getId() {return id;}
 public void setId(Integer id) {this.id = id;}

 @ManyToOne
 public OrganizationalType getType() {return type;}
 public void setType(OrganizationalType type) {
 System.out.println(" ------------ Type : " + type);
 this.type = type;
 }



}

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

import org.jboss.seam.annotations.Name;

@Entity
@Name("organizationalType")


public class OrganizationalType implements Serializable{

 /**
 *
 */
 private static final long serialVersionUID = 2490845589570967280L;
 private String type ;
 private Integer id;

 public OrganizationalType(){}

 public OrganizationalType(String type) {
 this.type = type;
 }

 @Id @GeneratedValue
 public Integer getId() {return id;}
 public void setId(Integer id) {this.id = id;}

 public String getType() {return type;}
 public void setType(String type) {this.type = type;}
}

<persistence:managed-persistence-context name="entityManager"
 auto-create="true"
 persistence-unit-jndi-name="java:/hopeEntityManagerFactory"/>

 <?xml version="1.0" encoding="UTF-8"?>
<!-- Persistence deployment descriptor for dev profile -->
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
 version="1.0">

 <persistence-unit name="hope">
 <provider>org.hibernate.ejb.HibernatePersistence</provider>
 <jta-data-source>java:/DefaultDS</jta-data-source>
 <properties>
 <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect" />
 <property name="hibernate.transaction.flush_before_completion" value="true" />
 <property name="hibernate.hbm2ddl.auto" value="create-drop" />
 <property name="hibernate.show_sql" value="true" />
 <property name="jboss.entity.manager.factory.jndi.name" value="java:/hopeEntityManagerFactory"/>
 </properties>
 </persistence-unit>

</persistence>