Erro HTTP Status 500 – Internal Server Error

Estou com seguinte erro abaixo, podem ajudar

Type Exception Report

Message Request processing failed; nested exception is java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: aluno is not mapped [select a from aluno a]

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: aluno is not mapped [select a from aluno a]
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:973)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Root Cause

java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: aluno is not mapped [select a from aluno a]
    org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1750)
    org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1677)
    org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1683)
    org.hibernate.jpa.spi.AbstractEntityManagerImpl.createQuery(AbstractEntityManagerImpl.java:350)
    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.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:289)
    com.sun.proxy.$Proxy251.createQuery(Unknown Source)
    org.autoescola.sae.daos.AlunoDAO.listar(AlunoDAO.java:24)
    org.autoescola.sae.daos.AlunoDAO$$FastClassBySpringCGLIB$$1f35d0f7.invoke(<generated>)
    org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
    org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
    org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:98)
    org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:266)
    org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653)
    org.autoescola.sae.daos.AlunoDAO$$EnhancerBySpringCGLIB$$330775fc.listar(<generated>)
    org.autoescola.sae.controller.AlunosController.alunos(AlunosController.java:33)
    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.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:781)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:721)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943)

classe

package org.autoescola.sae.daos;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.autoescola.sae.models.Aluno;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

@Repository
@Transactional
public class AlunoDAO {

    @PersistenceContext
    private EntityManager manager;

    public void gravar(Aluno aluno) {
        manager.persist(aluno);
    }

    public List<Aluno> listar() {        
        return manager.createQuery("select a from aluno a", Aluno.class).getResultList();
    }

}