jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class

Question

I am running a Maven project which is also a dynamic web project. I have used all Spring libraries in Maven. I created web.xml, but when I start my Tomcat 7 ser

Answer 1

Typically when you see this message, it is benign. If it says

INFO: validateJarFile(//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

It means it is ignoring your servlet-api-2.5.jar because tomcat already has a built-in version of that jar, so it isn't going to be using yours. Typically this doesn't cause an issue.

If however it says WEB-INF/lib/my_jar.jar - jar not loaded...Offending class: javax/servlet/Servlet.class

then what you can do (in my instance, it's a shaded jar) is run

$ mvn dependency:tree

and discover that you have a transitive dependency on "something" that depends on a jar that is either servlet-api or something like it (ex: tomcat-servlet-api-9.0.0). So add an exclusion to that to your pom, ex: (in my case, tomcat, in your case, probably the ones mentioned in the other answers):

 
    ...
    
      
        org.apache.tomcat
        tomcat-servlet