How to debug IncompatibleClassChange error in a Java War project (Jersey)?

Question

I understand what the error is: There is a jar with a class that is not what the caller is expecting. My problem is that the error does not tell me the offending class or jar in my dependency tree. I'll tell you a bit about my project, and then I'll post the error itself. Again, I'm mostly trying to learn how to debug such an error in general. Solving the problem is a bonus for me. Are there any run-time analysis tools for WAR files? Is there something in the error that I am missing?

Project It's a Jersey project, running on Tomcat. I am using eclipse for development. It's also a Maven project. It has a dependency on another project which is one of our projects. After digging, it seems the conflict is with a sub-dependency of our project.

Error

Jan 15, 2014 9:47:21 AM org.apache.catalina.core.ApplicationContext log
SEVERE: StandardWrapper.Throwable
java.lang.IncompatibleClassChangeError: Implementing class
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:2918)
    at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:1174)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1669)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1547)
    at org.glassfish.jersey.server.ResourceConfig.scanClasses(ResourceConfig.java:875)
    at org.glassfish.jersey.server.ResourceConfig._getClasses(ResourceConfig.java:840)
    at org.glassfish.jersey.server.ResourceConfig.getClasses(ResourceConfig.java:755)
    at org.glassfish.jersey.server.ResourceConfig$RuntimeConfig.<init>(ResourceConfig.java:1171)
    at org.glassfish.jersey.server.ResourceConfig$RuntimeConfig.<init>(ResourceConfig.java:1144)
    at org.glassfish.jersey.server.ResourceConfig.createRuntimeConfig(ResourceConfig.java:1140)
    at org.glassfish.jersey.server.ApplicationHandler.<init>(ApplicationHandler.java:299)
    at org.glassfish.jersey.servlet.WebComponent.<init>(WebComponent.java:311)
    at org.glassfish.jersey.servlet.ServletContainer.init(ServletContainer.java:169)
    at org.glassfish.jersey.servlet.ServletContainer.init(ServletContainer.java:359)
    at javax.servlet.GenericServlet.init(GenericServlet.java:160)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1280)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1193)
    at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:865)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:136)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
    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:744)

Jan 15, 2014 9:47:21 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Allocate exception for servlet Jersey Web Application
java.lang.IncompatibleClassChangeError: Implementing class
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:2918)
    at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:1174)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1669)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1547)
    at org.glassfish.jersey.server.ResourceConfig.scanClasses(ResourceConfig.java:875)
    at org.glassfish.jersey.server.ResourceConfig._getClasses(ResourceConfig.java:840)
    at org.glassfish.jersey.server.ResourceConfig.getClasses(ResourceConfig.java:755)
    at org.glassfish.jersey.server.ResourceConfig$RuntimeConfig.<init>(ResourceConfig.java:1171)
    at org.glassfish.jersey.server.ResourceConfig$RuntimeConfig.<init>(ResourceConfig.java:1144)
    at org.glassfish.jersey.server.ResourceConfig.createRuntimeConfig(ResourceConfig.java:1140)
    at org.glassfish.jersey.server.ApplicationHandler.<init>(ApplicationHandler.java:299)
    at org.glassfish.jersey.servlet.WebComponent.<init>(WebComponent.java:311)
    at org.glassfish.jersey.servlet.ServletContainer.init(ServletContainer.java:169)
    at org.glassfish.jersey.servlet.ServletContainer.init(ServletContainer.java:359)
    at javax.servlet.GenericServlet.init(GenericServlet.java:160)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1280)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1193)
    at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:865)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:136)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
    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:744)

Answer 1

It's also a Maven project. It has a dependency on another project which is one of our projects. After digging, it seems the conflict is with a sub-dependency of our project.

Check that all of your projects are using the same version of Jersey and the same version of any other major frameworks that your project uses. Use the Maven dependency analysis tool in Eclipse to show what JARs are being included in your WAR and what dependency declaration is causing the JAR to be included.

You may need to add exclusions in your POM to fix things. For example, so that some ancillary dependency doesn't pull in an outdated version of Jersey.

Are there any run-time analysis tools for WAR files?

You can add -verbose:class to your Java options to get a printout of classes and JARs as they are loaded.