Olá Chryss

Parece que esse é um erro do plugin de integração do eclipse com o tomcat. Para corrigir, tente fazer os seguintes passos:

• Dentro do eclipse, abra a aba Servers e pare o tomcat.

• Clique com o botão direito no tomcat e escolha a opção Add and Remove e na janela que é aberta, remova o seu projeto do tomcat e depois clique em finish.

• Na aba servers novamente, clique com o botão direito no tomcat e escolha a opção Clean.

• Por fim, entre novamente no Add and Remove e adicione novamente seu projeto no servidor

• Depois de executar todos os passos, Teste novamente a aplicação.

Olá Victor,

Fiz o que você falou, mas o erro continua.

Set 19, 2014 10:14:08 AM org.apache.catalina.core.AprLifecycleListener init
INFORMAÇÕES: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: /usr/java/packages/lib/amd64:/usr/lib/x86_64-linux-gnu/jni:/lib/x86_64-linux-gnu:/usr/lib/x86_64-linux-gnu:/usr/lib/jni:/lib:/usr/lib
Set 19, 2014 10:14:08 AM org.apache.tomcat.util.digester.SetPropertiesRule begin
ADVERTÊNCIA: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:vraptor-produtos' did not find a matching property.
Set 19, 2014 10:14:09 AM org.apache.coyote.AbstractProtocol init
INFORMAÇÕES: Initializing ProtocolHandler ["http-bio-8080"]
Set 19, 2014 10:14:09 AM org.apache.coyote.AbstractProtocol init
INFORMAÇÕES: Initializing ProtocolHandler ["ajp-bio-8009"]
Set 19, 2014 10:14:09 AM org.apache.catalina.startup.Catalina load
INFORMAÇÕES: Initialization processed in 1494 ms
Set 19, 2014 10:14:09 AM org.apache.catalina.core.StandardService startInternal
INFORMAÇÕES: Starting service Catalina
Set 19, 2014 10:14:09 AM org.apache.catalina.core.StandardEngine startInternal
INFORMAÇÕES: Starting Servlet Engine: Apache Tomcat/7.0.55
log4j:WARN No appenders could be found for logger (org.jboss.logging).
log4j:WARN Please initialize the log4j system properly.
Set 19, 2014 10:14:29 AM org.apache.catalina.core.StandardContext listenerStart
GRAVE: Exception sending context initialized event to listener instance of class org.jboss.weld.environment.servlet.Listener
org.jboss.weld.exceptions.DeploymentException: br/com/caelum/vraptor/events/ControllerMethodDiscovered
    at org.jboss.weld.executor.AbstractExecutorServices.checkForExceptions(AbstractExecutorServices.java:66)
    at org.jboss.weld.executor.AbstractExecutorServices.invokeAllAndCheckForExceptions(AbstractExecutorServices.java:43)
    at org.jboss.weld.executor.AbstractExecutorServices.invokeAllAndCheckForExceptions(AbstractExecutorServices.java:51)
    at org.jboss.weld.bootstrap.ConcurrentBeanDeployer.createClassBeans(ConcurrentBeanDeployer.java:72)
    at org.jboss.weld.bootstrap.BeanDeployment.createBeans(BeanDeployment.java:260)
    at org.jboss.weld.bootstrap.WeldStartup.deployBeans(WeldStartup.java:351)
    at org.jboss.weld.bootstrap.WeldBootstrap.deployBeans(WeldBootstrap.java:79)
    at org.jboss.weld.environment.servlet.Listener.contextInitialized(Listener.java:170)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4992)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5490)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1575)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1565)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    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:745)
Caused by: java.lang.NoClassDefFoundError: br/com/caelum/vraptor/events/ControllerMethodDiscovered
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2570)
    at java.lang.Class.getDeclaredMethods(Class.java:1855)
    at java.lang.Class.getEnclosingMethod(Class.java:932)
    at org.jboss.weld.util.reflection.Reflections.isNonStaticInnerClass(Reflections.java:388)
    at org.jboss.weld.util.Beans.isTypeManagedBeanOrDecoratorOrInterceptor(Beans.java:486)
    at org.jboss.weld.bootstrap.BeanDeployer.createClassBean(BeanDeployer.java:233)
    at org.jboss.weld.bootstrap.ConcurrentBeanDeployer$2.doWork(ConcurrentBeanDeployer.java:74)
    at org.jboss.weld.bootstrap.ConcurrentBeanDeployer$2.doWork(ConcurrentBeanDeployer.java:72)
    at org.jboss.weld.executor.IterativeWorkerTaskFactory$1.call(IterativeWorkerTaskFactory.java:60)
    at org.jboss.weld.executor.IterativeWorkerTaskFactory$1.call(IterativeWorkerTaskFactory.java:53)
    ... 4 more
Caused by: java.lang.ClassNotFoundException: br.com.caelum.vraptor.events.ControllerMethodDiscovered
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
    ... 15 more

Set 19, 2014 10:14:29 AM org.apache.catalina.core.StandardContext startInternal
GRAVE: Error listenerStart
Set 19, 2014 10:14:29 AM org.apache.catalina.core.StandardContext startInternal
GRAVE: Context [/vraptor-produtos] startup failed due to previous errors
Set 19, 2014 10:14:29 AM org.apache.catalina.core.StandardContext listenerStop
GRAVE: Exception sending context destroyed event to listener instance of class org.jboss.weld.environment.servlet.Listener
java.lang.NullPointerException
    at org.jboss.weld.servlet.WeldInitialListener.contextDestroyed(WeldInitialListener.java:102)
    at org.jboss.weld.servlet.api.helpers.ForwardingServletListener.contextDestroyed(ForwardingServletListener.java:30)
    at org.jboss.weld.environment.servlet.Listener.contextDestroyed(Listener.java:85)
    at org.apache.catalina.core.StandardContext.listenerStop(StandardContext.java:5033)
    at org.apache.catalina.core.StandardContext.stopInternal(StandardContext.java:5685)
    at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:232)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:160)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1575)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1565)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    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:745)

Set 19, 2014 10:14:30 AM org.apache.coyote.AbstractProtocol start
INFORMAÇÕES: Starting ProtocolHandler ["http-bio-8080"]
Set 19, 2014 10:14:30 AM org.apache.coyote.AbstractProtocol start
INFORMAÇÕES: Starting ProtocolHandler ["ajp-bio-8009"]
Set 19, 2014 10:14:30 AM org.apache.catalina.startup.Catalina start
INFORMAÇÕES: Server startup in 20643 ms

Você poderia postar o conteúdo do arquivo pom.xml?

Claro...

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>br.com.caelum</groupId>
    <artifactId>vraptor-produtos</artifactId>
    <version>1.0.0</version>
    <packaging>war</packaging>

    <description>Um projeto de produtos e estoque com VRaptor 4</description>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>br.com.caelum</groupId>
            <artifactId>vraptor</artifactId>
            <version>4.0.0.Final</version>
        </dependency>

        <dependency>
            <groupId>br.com.caelum.vraptor</groupId>
            <artifactId>vraptor-jpa</artifactId>
            <version>4.0.1</version>
        </dependency>

<!--         <dependency> -->
<!--             <groupId>br.com.caelum.vraptor</groupId> -->
<!--             <artifactId>vraptor-simplemail</artifactId> -->
<!--             <version>4.0.0-RC2</version> -->
<!--         </dependency> -->

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator-cdi</artifactId>
            <version>5.0.2.Final</version>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>4.3.0.Final</version>
        </dependency>

        <dependency>
            <groupId>org.hsqldb</groupId>
            <artifactId>hsqldb</artifactId>
            <version>2.3.0</version>
        </dependency>

        <dependency>
            <groupId>org.jboss.weld.servlet</groupId>
            <artifactId>weld-servlet</artifactId>
            <version>2.1.1.Final</version>
        </dependency>

        <dependency>
            <groupId>javax.el</groupId>
            <artifactId>el-api</artifactId>
            <version>2.2</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.6.0</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.6.0</version>
        </dependency>
    </dependencies>

    <build>
        <finalName>vraptor-produtos</finalName>
        <outputDirectory>${basedir}/src/main/webapp/WEB-INF/classes</outputDirectory>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>

            <plugin>
                <artifactId>maven-eclipse-plugin</artifactId>
                <version>2.8</version>
                <configuration>
                    <downloadSources>true</downloadSources>
                    <downloadJavadocs>true</downloadJavadocs>
                    <wtpversion>2.0</wtpversion>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.4</version>
            </plugin>

            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.1</version>
            </plugin>

            <plugin>
                <groupId>org.mortbay.jetty</groupId>
                <artifactId>maven-jetty-plugin</artifactId>
                <version>6.1.26</version>
                <configuration>
                    <scanIntervalSeconds>3</scanIntervalSeconds>
                    <stopKey>foo</stopKey>
                    <stopPort>9999</stopPort>
                    <webAppConfig>
                        <contextPath>/</contextPath>
                    </webAppConfig>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-deploy-plugin</artifactId>
                <version>2.8</version>
                <configuration>
                    <skip>true</skip>
                </configuration>
            </plugin>

            <plugin>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>2.3</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <configuration>
                            <descriptors>
                                <descriptor>assembly.xml</descriptor>
                            </descriptors>
                        </configuration>
                        <goals>
                            <goal>assembly</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

Oi Chryss

Tente trocar a versão do plugin vraptor-jpa para 4.0.0.Final no seu pom.xml

Atualmente o versionamento dos plugins do VRaptor está tentando seguir o versionamento do próprio VRaptor, então se o VRaptor estiver na versão 4.0.0, o plugin também estará na versão 4.0.0.

Qdo baixei o projeto, estava na versão 4.0.0, porém não compilou.Vi a resposta do exercício com 4.0.1, alterei e compilou, porém deu este erro.

Funcionou, obrigada!

Eu sei que este problema está resolvido, porém tive um probleminha com esse plugin quando atualizei meu projeto para a versão 4.1.0.FINAL do Vraptor e gostaria de compartilhar a solução. O projeto não subia e resolvi atualizar o vraptor-jpa para a versão 4.0.2 e funcionou normalmente. ;D