Tomcat 7 LinkageError: loader constraint violation

Question

INFO: Deploying web application archive test-1.0-SNAPSHOT.war
20-Sep-2011 12:08:42 org.apache.catalina.loader.WebappClassLoader validateJarFile
INFO: validateJarFile(C:\software\apache-tomcat-7.0.21\webapps\test-1.0-SNAPSHOT\WEB-INF\lib\servlet-api-2.5.jar) - jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class
20-Sep-2011 12:08:42 com.sun.faces.config.ConfigureListener contextInitialized
INFO: Initializing Mojarra 2.1.0 (SNAPSHOT 20100817) for context '/test-1.0-SNAPSHOT'
20-Sep-2011 12:08:42 com.sun.faces.spi.InjectionProviderFactory createInstance
INFO: JSF1048: PostConstruct/PreDestroy annotations present.  ManagedBeans methods marked with these annotations will have said annotations processed.
20-Sep-2011 12:08:43 com.sun.faces.config.ConfigureListener contextInitialized
SEVERE: Critical error during deployment: 
java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;" the class loader (instance of org/apache/catalina/loader/WebappClassLoader) of the current class, com/sun/faces/config/ConfigureListener, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for resolved class, javax/servlet/jsp/JspApplicationContext, have different Class objects for the type javax/el/ExpressionFactory used in the signature
    at com.sun.faces.config.ConfigureListener.registerELResolverAndListenerWithJsp(ConfigureListener.java:684)
    at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:240)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4723)
    at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5226)
    at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5221)
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
20-Sep-2011 12:08:43 org.apache.catalina.core.StandardContext listenerStart
SEVERE: Exception sending context initialized event to listener instance of class com.sun.faces.config.ConfigureListener
java.lang.RuntimeException: java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;" the class loader (instance of org/apache/catalina/loader/WebappClassLoader) of the current class, com/sun/faces/config/ConfigureListener, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for resolved class, javax/servlet/jsp/JspApplicationContext, have different Class objects for the type javax/el/ExpressionFactory used in the signature
    at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:290)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4723)
    at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5226)
    at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5221)
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;" the class loader (instance of org/apache/catalina/loader/WebappClassLoader) of the current class, com/sun/faces/config/ConfigureListener, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for resolved class, javax/servlet/jsp/JspApplicationContext, have different Class objects for the type javax/el/ExpressionFactory used in the signature
    at com.sun.faces.config.ConfigureListener.registerELResolverAndListenerWithJsp(ConfigureListener.java:684)
    at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:240)
    ... 8 more
20-Sep-2011 12:08:43 org.apache.catalina.core.StandardContext startInternal
SEVERE: Error listenerStart
20-Sep-2011 12:08:43 org.apache.catalina.core.StandardContext startInternal
SEVERE: Context [/test-1.0-SNAPSHOT] startup failed due to previous errors

I am trying to run mkyong hello world JSF2 example http://www.mkyong.com/jsf2/jsf-2-0-hello-world-example/

POM.xml is

<dependency>
        <groupId>com.sun.faces</groupId>
        <artifactId>jsf-api</artifactId>
        <version>2.1.0-b03</version>
    </dependency>
    <dependency>
        <groupId>com.sun.faces</groupId>
        <artifactId>jsf-impl</artifactId>
        <version>2.1.0-b03</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>

    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>servlet-api</artifactId>
        <version>2.5</version>
    </dependency>

    <dependency>
        <groupId>javax.servlet.jsp</groupId>
        <artifactId>jsp-api</artifactId>
        <version>2.1</version>
    </dependency>

    <dependency>
        <groupId>com.sun.el</groupId>
        <artifactId>el-ri</artifactId>
        <version>1.0</version>
        <scope>provided</scope>
    </dependency>

This thread loader constraint violation describes same issue in tomcat 6 but it is not help to solve my issue.

Answer 1

I don't do Maven, but given the answer of Pascal Thivent in your linked question, it seems that you need to mark a Maven dependency as provided whenever the target runtime already ships with it out the box.

Tomcat as being a simple servletcontainer ships with JSP, Servlet and EL out the box (only not with JSF and JSTL). The exception message which you got indicates duplication of the JSP API in the classpath. I suggest to set the JSP and Servlet entries in your pom.xml to provided as well.

Further, you will get a second major problem after you fix the problem as stated in the question, Mojarra 2.1.0 does not work in Tomcat. Upgrade to Mojarra 2.1.1 or newer (it's currently at 2.1.3). See also the Mojarra download page for pom snippets.