Action class [action.SubscribeAction] not found - action - file: struts.xml

I want to add an action to my struts.xml, but when I do it my webapp stops working, and I don't know why. I post here some details of my webapp.

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>ILIMobileLeborgne</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>

  <filter>
   <filter-name>struts2</filter-name>
   <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
  </filter>

  <filter-mapping>
    <filter-name>struts2</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
</web-app>

struts.xml (in the src folder in Eclipse):

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>

<constant name="struts.devMode" value="true" />
<constant name="struts.custom.i18n.resources" value="ilimobile" />

<package name="ilimobile" namespace="/" extends="struts-default">

    <action name="index">
        <result>/index.jsp</result>
    </action>
    
    <action name="registerIllimite">
        <result>/registerIllimite.jsp</result>
    </action>
    
      <!-- When I try to do add the following action, my app doesn't work, the browser said me that the ressource asked is unavailable, and when I delete it, my (little) app works correctly -->
    <action name="registerClientInfo"  class="action.SubscribeAction">
        <result name="success">/paiement.jsp</result>
    </action>

</package>

</struts>

My SubscribeAction (in the action package in the source folder):

package action;

import model.*;

import com.opensymphony.xwork2.ActionSupport;

public class SubscribeAction extends ActionSupport {
private Client client;
private String abonnement;

public String getAbonnement() {
    return abonnement;
}

public void setAbonnement(String abonnement) {
    this.abonnement = abonnement;
}

@Override
public String execute() throws Exception {
    // TODO Auto-generated method stub
    return SUCCESS;
}

public Client getClient() {
    return client;
}

public void setClient(Client client) {
    this.client = client;
}
}

And my JSP page which use the action defined:

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%> 
<%@ taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
 <head>
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  <title>Insert title here</title>
 </head>
 <body>
<s:form action="registerClientInfo">
    <s:textfield key="client.nom"/>
    <s:textfield key="client.prenom"/>
    <s:textfield key="client.email"/>
    <s:textfield key="client.adresse"/>
    <s:textfield key="client.ville"/>
    <s:textfield key="client.cp"/>
    
    <s:submit/>
</s:form>
 </body>
</html>

If you need some extra info, ask me, but I think you could see why my app doesn't want to work. I'm pretty sure that it's just a little error, but I can't find it..

EDIT:

I post here the Eclipse stacktrace which shows me that it can't find my action class, but I don't know why. I've a Struts 2 example made by my teacher and I don't think that he made some extra steps to deploy the app with a Tomcat server on Eclipse.

The stacktrace:

Unable to load configuration. - action - file:/home/blackmario/workspace/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/ILIMobileLeborgne/WEB-INF/classes/struts.xml:20:68
    at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:70)
    at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:429)
    at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:471)
    at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:74)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:51)
    at org.apache.catalina.core.ApplicationFilterConfig.initFilter(ApplicationFilterConfig.java:277)
    at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:258)
    at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:382)
    at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:103)
    at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4650)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5306)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
    at java.util.concurrent.FutureTask.run(FutureTask.java:166)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at java.lang.Thread.run(Thread.java:722)


Caused by: Action class [action.SubscribeAction] not found - action - file:/home/blackmario/workspace/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/ILIMobileLeborgne/WEB-INF/classes/struts.xml:20:68
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.verifyAction(XmlConfigurationProvider.java:480)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addAction(XmlConfigurationProvider.java:424)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addPackage(XmlConfigurationProvider.java:541)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadPackages(XmlConfigurationProvider.java:290)
    at org.apache.struts2.config.StrutsXmlConfigurationProvider.loadPackages(StrutsXmlConfigurationProvider.java:112)
    at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:239)
    at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:67)
    ... 18 more

Solution

So, it sounds like your application fails to start when you add that action, correct? Nothing works, even the ones that worked before. So, you should look in the logs of the servlet container you are using. Nothing is more fundamental that finding where the logs are and becoming familiar with them.

When you do look in the logs, I'm guessing you'll see either

1) an error complaining that the syntax of the struts.xml is bad and the application fails when trying to parse it.

2) A ClassNotFoundException because the class file for that action is not on the classpath of the application. If this is the case make sure that the class files for that action are actually being put into the WAR file's WEB-INF/lib or WEB-INF/classes direcgtory; that's where a webapp's classloader looks for class files. If you don't know much about this, you should read more about Java Servlets.

Both of these are things that might cause the application to not successfully start. You must look at the logs; they will amost always tell you that the application had a specific issue. If you ask about that specific issue on this forum, you'll get very useful answers. Otherwise, I'm kind of guessing.