ViewExpiredException when i use @ViewScoped

I have problem with my h:commandButton "Login": when I use @ViewScoped and push this button there is ViewExpiredException, but when I use @SessionScoped, there isn't any error.

Stack Trace:

javax.faces.application.ViewExpiredException: /pages/register.xhtmlNo saved view state could be found for the view identifier: /pages/register.xhtml
at org.apache.myfaces.lifecycle.RestoreViewExecutor.execute(RestoreViewExecutor.java:132)
at org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:170)
at org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:117)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:197)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:79)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
at org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
at org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:724)

my page:

            <h:form>
                <h:panelGrid columns="2" >
                    <h:outputLabel value="Login:"/>
                    <h:inputText value="#{registerController.registerLog}"/>
                    <h:outputLabel value="#{msg.password}"/>
                    <h:inputSecret id="pass" value=""/>

                    <h:column/>
                    <h:commandButton value="Login" action="#{registerController.login}"/> 

                </h:panelGrid> 
            </h:form>

and this is my RegisterController class:

@ManagedBean
@ViewScoped
public class RegisterController {

private String registerLog = "";
private String registerPass = "";


/**
 * Creates a new instance of RegisterController
 */
public RegisterController() {
}

//getters, setters

public String login(){

    return null;

}

Your concrete problem is caused because your view scoped bean is not serializable and hence MyFaces is not able to save it in the view state. MyFaces by default serializes the whole state in session instead of just referencing the state in session and having the container to serialize it if necessary.

There are basically 2 solutions:

1. Let your view scoped bean implement Serializable.

2. Tell MyFaces to not serialize the whole view state in session.

   <context-param>
       <param-name>org.apache.myfaces.SERIALIZE_STATE_IN_SESSION</param-name>
       <param-value>false</param-value>
   </context-param>
   

   Note that the view scoped bean will still be lost whenever you restart the server.