尝试在 spring 项目中进行注册时无法提交 JPA 事务

Question

I am using netbeans ide for Spring project. I am continuously getting the error could not commit jpa transaction on trying to do the registration (saving data on MySQL database). This is the error stack:

There was an unexpected error (type=Internal Server Error, status=500). Could not commit JPA transaction; nested exception is javax.persistence.RollbackException: Error while committing the transaction org.springframework.transaction.TransactionSystemException: Could not commit JPA transaction; nested exception is javax.persistence.RollbackException: Error while committing the transaction at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:571) at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:743) at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:711) at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:654) at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:407) at org.springframework.transaction.interceptor.TransactionInt erceptor.invoke(TransactionInterceptor.java:119) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:137) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:174) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterce ptor.java:97) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215) at jdk.proxy4/jdk.proxy4.$Proxy108.save(Unknown Source) at net.cdac.TMS.service.UserServiceImpl.save(UserServiceImpl.java:38) at net.cdac.TMS.web.UserRegistrationController.registerUserAccount(UserRegistrationController.java:36) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Del egatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:568) at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) at org.springframework.web.s ervlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1070) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909) at javax.servlet.http.HttpServlet.serv ice(HttpServlet.java:681) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) at org.ZB6EFD606D1 18D0F62066E31419FF04CCZ.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:327) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:115) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:81) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.Z93F725A07423FE1C889F448B 33D21F46Z:122) at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:116) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:126) at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:81) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.authen tication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:109) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:149) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.Z93F725A07423FE1C889F448B33D21F4 6Z:336) at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:223) at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:217) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:103) at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:89) at org.springframework.security.web.FilterChain Proxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:132) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:90) at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:75) at org.springframework.Z2567A5EC9705EB7AC2C 984033E06189DZ.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:112) at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:82) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilte r.java:55) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.session.DisableEncodeUrlFilter.doFilterInternal(DisableEncodeUrlFilter.java:42) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.FilterChainProxy.doFilterInternal(Filt erChainProxy.java:211) at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:183) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:354) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:267) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) a t org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) at org.apache.catalina.core.Applica tionFilterChain.doFilter(ApplicationFilterChain.java:162) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.Z93F725A07423FE1C889F448B3 3D21F46Z:97) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:360) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) at or g.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:890) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1789) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.Z93F725A07423FE1C889F44 8B33D21F46Z:61) at java.base/java.lang.Thread.run(Thread.java:833) Caused by: javax.persistence.RollbackException: Error while committing the transaction at org.hibernate.internal.ExceptionConverterImpl.convertCommitException(ExceptionConverterImpl.java:81) at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:104) at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:562)... 110 more Caused by: java.lang.ClassCastException: class net.cdac.TMS.model.User cannot be cast to class java.ZF98ED07A4D5F50F7DE1410D905F1477F Z.Serializable (net.cdac.TMS.model.User is in unnamed module of loader org.springframework.boot.devtools.restart.classloader.RestartClassLoader @4df620d4; java.io.Serializable is in module java.base of loader 'bootstrap') at org.hibernate.type.CollectionType.getKeyOfOwner(CollectionType.java:446) at org.hibernate.engine.internal.Collections.processReachableCollection(Collections.java:166) at org.hibernate.event.internal.FlushVisitor.processCollection(FlushVisitor.java:53) at org.hibernate.event.internal.AbstractVisitor.processValue(AbstractVisitor.java:104) at org.hibernate.event.internal.AbstractVisitor.processValue(AbstractVisitor.java:65) at org.hibernate.event.internal.AbstractVisitor.processEntityPropertyValues(AbstractVisito r.java:59) at org.hibernate.event.internal.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:183) at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:107) at org.hibernate.event.internal.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:229) at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:93) at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:39) at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventO nEachListener(EventListenerGroupImpl.java:107) at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1407) at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:489) at org.hibernate.internal.SessionImpl.flushBeforeTransactionCompletion(SessionImpl.java:3290) at org.hibernate.internal.SessionImpl.beforeTransactionCompletion(SessionImpl.java:2425) at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.beforeTransactionCompletion(JdbcCoordinatorImpl.java:449) at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.beforeCompletionCa llback(JdbcResourceLocalTransactionCoordinatorImpl.java:183) at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.access$300(JdbcResourceLocalTransactionCoordinatorImpl.java:40) at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.commit(JdbcResourceLocalTransactionCoordinatorImpl.java:281) at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:101)... 111 more

The Role.java code:

package net.cdac.TMS.model;

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

@Entity
@Table(name = "role")
public class Role {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;

    public Role() {

    }

    public Role(String name) {
        super();
        this.name = name;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

The User.java code:

package net.cdac.TMS.model;

import java.util.Collection;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;
import javax.persistence.JoinColumn;

@Entity
@Table(name = "user", uniqueConstraints = @UniqueConstraint(columnNames = "uemailid"))
public class User {

    @GeneratedValue(strategy =  GenerationType.IDENTITY)
    private Long id;
    @Column(name = "uname")
    private String uName;


    @Id
    @Column(name = "uemailid")
    private String uemailid;

    private String upassword;

    private String usecurityQ;

    private String usecurityA;

    @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinTable(
            name = "users_roles",
            joinColumns = @JoinColumn(
                    name = "user_id", referencedColumnName = "id"),
            inverseJoinColumns = @JoinColumn(
                            name = "role_id", referencedColumnName = "id"))
    
    private Collection<Role> roles;
    public User() {

    }
    public User(String email, String password) {

    }

    public User(String Name, String email, String password, String securityQ, String securityA, Collection<Role> roles) {
        super();
        this.uName = Name;
        this.uemailid = email;
        this.upassword = password;
        this.usecurityA = securityQ;
        this.usecurityA = securityA;
        this.roles = roles;
    }

    public String getUemailid() {
        return uemailid;
    }

    public void setUemailid(String uemailid) {
        this.uemailid = uemailid;
    }
    
    public String getuName() {
        return uName;
    }

    public void setuName(String uName) {
        this.uName = uName;
    }

    public String getUpassword() {
        return upassword;
    }

    public void setUpassword(String upassword) {
        this.upassword = upassword;
    }

    public String getUsecurityQ() {
        return usecurityQ;
    }

    public void setUsecurityQ(String usecurityQ) {
        this.usecurityQ = usecurityQ;
    }

    public String getUsecurityA() {
        return usecurityA;
    }

    public void setUsecurityA(String usecurityA) {
        this.usecurityA = usecurityA;
    }
    public Collection<Role> getRoles() {
        return roles;
    }
    public void setRoles(Collection<Role> roles) {
        this.roles = roles;
    }

}

The login.html code:

<!DOCTYPE html>
<html>
    <head>
        <meta charset="ISO-8859-1">
        <title>User Login</title>
    </head>
    <body>
        <header>

            <div class="header-1">
                <img class="logo" src="../images/cdacW.png" alt="C-DAC">
            </div>
        </header>
        <div class="form-center">
            <div class="center">
                <h1>Login</h1>
                <form th:action="@{/UserLogin}" method="post">
                    <!-- error message -->
                    <div th:if="${param.error}">
                        <div class="alert alert-danger">Invalid username or
                            password.</div>
                    </div>

                    <!-- logout message -->
                    <div th:if="${param.logout}">
                        <div class="alert alert-info">You have been logged out.</div>
                    </div>
                    
                    <div class="txt_field">
                        <input type="text" required>
                        <span></span>
                        <label>Email ID</label>
                    </div>
                    <div class="txt_field">
                        <input type="password" required>
                        <span></span>
                        <label>Password</label>
                    </div>
                    <div class="pass"><a href="/" th:href="@{/forgotPasswordUser}">Forgot Password?</a></div>
                    <input type="submit" value="Login">
                    <div class="signup_link">
                        Not a member? <a href="/" th:href="@{/registration}">Sign-Up</a>
                    </div>
                </form>
            </div>
        </div>
    </body>
</html>

The registeration.html code:

<!DOCTYPE html>
<html>
    <head>
        <title>Register</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.15.2/css/all.min.css">
    </head>

    <body>
        <header>
            <div class="header-1">
                <img class="logo" src="../images/cdacW.png" alt="C-DAC">
            </div>
        </header>
        <!-- success message -->
        <div th:if="${param.success}">
            <div class="alert alert-info">You have successfully registered!</div>
        </div>
        <div class="registeration-form"> 
            <h1>Register here</h1> 
            <form th:action="@{/registration}" method="post" th:object="${user}">
                <p>Full Name : </p>
                <input type="text" name="fullname" placeholder = "Full Name" th:field="*{uName}">  
                <p>Email id: </p>
                <input type="email" name="email" placeholder = "Email Id" th:field="*{uemail}">  
                <p>Password : </p>
                <input type="password" name="password" placeholder = "Password" th:field="*{upassword}" required autofocus="autofocus">  
                <p>Photo: </p>
                <!--input type="image" name="image" placeholder = "your photo"-->
                <p>Security Question: </p>
                <label for="SecurityQ"> </label>

                <select name="securityq" id="securityq" th:field="*{usecurityQ}">
                    <option value="Your Favourite color ">Your Favourite color</option>
                    <option value="Your first pet's name">Your first pet's name</option>
                    <option value="Your mother's maiden name">Your mother's maiden name</option>
                    <option value="Your first school">Your first school</option>
                    <option value="Your Favourite food ">Your Favourite food</option>
                    <option value="The city you live in">The city you live in</option>
                </select>
                <p>Security Answer : </p>
                <input type="text" name="securityA" placeholder = "Your answer" th:field="*{usecurityA}">  
                <p><button type="submit">Register</button></p>

                <h5>Already have an account? </h5>
                <h4><a href="/" th:href="@{/UserLogin}"> Login</a></h4>
            </form>
        </div>
    </body>
</html>

The UserRegisterationController.java code:

package net.cdac.TMS.web;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;

import net.cdac.TMS.service.UserService;
import net.cdac.TMS.web.dto.UserRegistrationDto;

@Controller
@RequestMapping("/registration")
public class UserRegistrationController {

    private UserService userService;

    public UserRegistrationController(UserService userService) {
        super();
        this.userService = userService;
    }
    
    @ModelAttribute("user")
    public UserRegistrationDto userRegistrationDto() {
        return new UserRegistrationDto();
    }
    
    @GetMapping
    public String showRegistrationForm() {
        return "registration";
    }
    
    @PostMapping
    public String registerUserAccount(@ModelAttribute("user") UserRegistrationDto registrationDto) {
        userService.save(registrationDto);
        return "redirect:/registration?success";
    }
}

The mainController.java code:

package net.cdac.TMS.web;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

@Controller
public class MainController {
    
    @GetMapping("/UserLogin")
    public String login() {
        return "UserLogin";
    }
    
    @GetMapping("/")
    public String home() {
        return "GuestHome";
    }
}

How to remove this error? What is the cause of this error? Thank you in advance for the help.

Answer 1

Always check caused by for any exception you get. For you:

 Caused by: java.lang.ClassCastException: class net.cdac.TMS.model.User cannot be cast to class java.io.Serializable

Have your User class implement Serializable and that should fix it.