solution for java.lang.VerifyError in tomcat 7.0.23/jdk 1.6.x?

Question

When I deployed a maven 3.0.3 built webapp into tomcat 7.0.23 on Linux (java 1.6.x) and accessed posted my credentials in the login page, I got the following error. pom.xml references servlet 2.5, jsp 2.1 and JSTL 1.2.

Why would I get this Error ? what can I do to avoid it ?

I have other .war files deployed on the same tomcat instance and never faced this issue in those apps.

The 1st JSP(login.jsp) that I did a http GET didn't throw an error. The POST from the 1st JSP to the 2nd Jsp(ChLogin.jsp) encountered the problem.

===========================

root cause

java.lang.VerifyError: (class: org/apache/jsp/ChLogin_jsp, method: _jspService signature: (Ljavax/servlet/http/HttpServletRequest;Ljavax/servlet/http/HttpServletResponse;)V) Inconsistent stack height 0 != 1
    java.lang.Class.getDeclaredConstructors0(Native Method)
    java.lang.Class.privateGetDeclaredConstructors(Class.java:2389)
    java.lang.Class.getConstructor0(Class.java:2699)
    java.lang.Class.newInstance0(Class.java:326)
    java.lang.Class.newInstance(Class.java:308)
    org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:172)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

UPDATE 1
the WEB-INF\lib of the webapp does NOT contain servlet, jsp or JSTL jars. It contains many application dependencies and spring jars (we use spring MVC).

UPDATE 2
We don't pre-compile JSPs. That is a goal for another day, though.

UPDATE 3
Discovered that this problem was not in tomcat 7.0.12, 7.0.14, 7.0.16 but started with 7.0.19. Posted to tomcat users mailing list. got a reply that it was perhaps the eclipse JDT compiler at fault. Verified that is indeed the case by replacing the compiler in tomcat 7.0.23/27 with tomcat 7.0.16's JDT compiler and LO & BEHOLD, all is well. I am planning to write to the Eclipse JDT compiler team(if there is one) and post about this error.

Answer 1

This error means the JSP has been compiled for a specific Servlet/JSP/JSTL implementation but then Tomcat tries to load compiled classes with an other implementation/version available in ClassPath.

It probably happens because your WAR contains jar files with servlet, jsp and/or jstl API and/or implementation. As used versions match Tomcat 5.5 imlementation, it works there but fail with more recent implementations.

You have to set the scope to provided for such dependencies in your Maven POM to exclude that jars from WAR WEB-INF/lib.

To validate that on-the-fly compiled code does not load alternate dependencies, you should run Tomcat with -verbose:class. Latest lines before the error may help to guess what is wrong.

Update 2012/05/30 Do you have any jasper or javax.el or el-api jar in WEB-INF/lib ? If so, remove it/them as well.

It is also possible that a taglib you used is specifically compiled for Tomcat 5.5 Servlet 2.3 API and breaks when Tomcat 7.