Do you have the Maven plugin installed/enabled?
As this copy artifact plugin depends on it, during compile time but there is no checking at runtime to see if it is installed before using it.

as indicated in
https://wiki.jenkins-ci.org/display/JENKINS/Dependencies+among+plugins

so code needs to be added to do the check for the plugin before use

if (Hudson.getInstance().getPlugin("maven-plugin") != null) {
// use classes in the "maven-plugin" plugin
}

> Do you have the Maven plugin installed/enabled?

No.

I see several maven plugins on our pluginManager/available page. Which one do you you mean?

The item is "Maven 2 Project Plugin" in the manage plugins pages, Is this listed as installed?

As by default this is included in the Jenkins war file .

Thanks. No, that's not installed.

I'll have to upgrade Jenkins to install that, because the pluginManager/available page says "Warning: This plugin is built for Jenkins 1.480.1 or newer. It may or may not work in your Jenkins."

I'm using the standard Ubuntu 12.10 (Quantal) package. I'll try the http://pkg.jenkins-ci.org/debian/ packages

Reproduced issue when maven-plugin is not installed.

Pull request
https://github.com/jenkinsci/copyartifact-plugin/pull/14

Yes, upgrading Jenkins seems to have fixed this. After upgrading to the jenkins.org .deb packages (1.493), there is no "Maven 2 Project plugin" available or installed, but the "Maven Integration plugin" seems to be installed by default.

And my "Copy artifacts from another project" build step now works.

Thanks.

I just ran into this problem with Jenkins version 1.524:

10:53:58 FATAL: hudson/maven/MavenModuleSetBuild
10:53:58 java.lang.NoClassDefFoundError: hudson/maven/MavenModuleSetBuild
10:53:58 at hudson.plugins.copyartifact.CopyArtifact.perform(CopyArtifact.java:221)
10:53:58 at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:19)
10:53:58 at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:804)
10:53:58 at hudson.model.Build$BuildExecution.build(Build.java:199)
10:53:58 at hudson.model.Build$BuildExecution.doRun(Build.java:160)
10:53:58 at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:586)
10:53:58 at hudson.model.Run.execute(Run.java:1593)
10:53:58 at hudson.matrix.MatrixRun.run(MatrixRun.java:146)
10:53:58 at hudson.model.ResourceController.execute(ResourceController.java:88)
10:53:58 at hudson.model.Executor.run(Executor.java:247)
10:53:58 Caused by: java.lang.ClassNotFoundException: hudson.maven.MavenModuleSetBuild
10:53:58 at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
10:53:58 at java.security.AccessController.doPrivileged(Native Method)
10:53:58 at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
10:53:58 at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
10:53:58 at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
10:53:58 at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:334)
10:53:58 ... 10 more

The problem was fixed by enabling the "Maven Integration plugin". I don't have any maven related configurations/jobs in this setup and therefore haven't had any Maven (related) plugins enabled so far, when upgrading from Jenkins 1.522 to 1.524 and also updating all related plugins this broke as noted above.

I had the same problem: upgrade from 1.523 to 1.524, NoClassDefFoundError, Maven Integration Plugin no longer in the list of installed plugins. All of my projects (maven) and build history were also gone, with a message about changes stored on disk that could not be migrated to the current format (under 'Manage Old Data'). I re-installed the plugin (from Manage Jenkins -> Manage Plugins), and everything worked again.

Code changed in jenkins
User: cjo9900
Path:
src/main/java/hudson/plugins/copyartifact/CopyArtifact.java
http://jenkins-ci.org/commit/copyartifact-plugin/6cd2d83c58527c87cfbcc174fdbf6f5767c8dcbd
Log:
[FIXED JENKINS-15977] ClassNotFound is maven plugin not installed

Check for the maven plugin being installed before trying to see
if the project src is a maven project.

Code changed in jenkins
User: ikedam
Path:
src/main/java/hudson/plugins/copyartifact/CopyArtifact.java
http://jenkins-ci.org/commit/copyartifact-plugin/d00c85521648361512e84ea0439ca6b1a95b9a4c
Log:
Merge pull request #14 from cjo9900/JENKINS-15977

[FIXED JENKINS-15977] ClassNotFound is maven plugin not installed

Compare: https://github.com/jenkinsci/copyartifact-plugin/compare/7df40f147030...d00c85521648