Java deploying war on Tomcat giving NoClassDefFoundError

Question

Here is an absurd scenario because I'm totally clueless why is this happening.

I have created a Java servlet, (maven) packaged as war to be deployed on Tomcat server. It works fine on 2 test machines (believe me) but when it is moved on another machine, any hit on that api gives NoClassDefFoundError for a particular class.

I've checked the unpacked Project directory in the webapps folder, and it contains that class.

What can be the reasons for this? I've checked all that I could but no clues anywhere. I know myself that it is not very clear a question but this is all I have.

Any other details, if required, ask for it in the comments.

Edit: (one more detail)

The Tomcat version is upgraded in this new machine...Previous machines have Apache Tomcat/7.0.59. This has Apache Tomcat/8.0.33. Can this be the problem?

EDIT:

I'm still not sure of the problem. After trying to find the issue for many hours, I re-configured the machine...re installed jdk and Tomcat and deployed on this and it worked.

It is possible that the class actually exists more than once in the classpath of the failing machine. — Koray Tugay, May 10 '16 at 07:21
@AlexanderKleinhans, there is no Manifest.mf file in the project. — vish4071, May 10 '16 at 07:23
@KorayTugay, The class has only one existence...I just checked. — vish4071, May 10 '16 at 07:24
Do the servers have the exact same version of Tomcat? Which classes exactly are not found? There must be some difference between the machines. — Jesper, May 10 '16 at 07:25
@Jesper, Yeah...the Tomcat version is upgraded in this new machine...Previous machines have `Apache Tomcat/7.0.59`. This has `Apache Tomcat/8.0.33`. Can this be the problem? — vish4071, May 10 '16 at 07:27
Delete the old/previous war files in the new machine and the deployed folder and redeploy the war again and see if it works. — Lucky, May 10 '16 at 07:40
I also had situation when project worked fine in local environment but failed with NoSuchMethodError in server. I have solved it with adding additional lib. — Justinas Jakavonis, May 10 '16 at 07:41
Do you maybe have a servlet API jar file in the `WEB-INF/lib` of your webapp? That should not be there and might clash with the servlet API that Tomcat provides. — Jesper, May 10 '16 at 07:55
@Jesper.. There is no servlet API jar file there. Do you think Tomcat version can be causing the problems.? — vish4071, May 10 '16 at 08:11
Yes, the Tomcat version can be the problem. It shouldn't, but you probably have something in your webapp that isn't quite right so that it doesn't work properly on Tomcat 8. But it's hard to tell exactly what that would be. — Jesper, May 10 '16 at 08:15

score 1 · Answer 1 · answered May 10 '16 at 07:27

1

My guess is that all the classes are there, but somewhere in the war file, there is class that uses another class that is in the classpath of the native, working machine, but not the other. NoClassDefinition is different from ClassNotFound, so the class is probably there (it should not be missing). Unfortunately, it sounds like there is a dependency that is not in the native war file, but still runs and compiles because it's in the native machine classpath.

Check your .bash_profile or wherever you export classpaths and you'll probably find some JAR file you need to put in the WAR.

Why am I getting a NoClassDefFoundError in Java?

answered May 10 '16 at 07:27

Alexander Kleinhans

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But the project has few dependencies which are put in `pom.xml`...no Custom jars are included. There are 4 packages though, which talk among themselves, and they are there in classes folder as they should be. – vish4071 May 10 '16 at 07:31
Again, only a hypothesis. `NoClassDefFoundError` does not mean the class is not there, it is defiantly there if you unpack the war file, otherwise you would be seeing `ClassNotFound`. Some class BEING USED the class inside the war file (which is not missing) is USING another class that is NOT in the war file, hence the DEFINITION is missing, not the CLASS. My guess is that it is in the `classpath` of the native machine, which is why it originally resolved correctly, but not on the new machine where the `classpath` is different. – Alexander Kleinhans May 10 '16 at 07:38

Java deploying war on Tomcat giving NoClassDefFoundError

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