When I excute shell 

xcodebuild -workspace "$MWProjectName.xcworkspace" -scheme "$MWScheme" -archivePath "$MWBuildDir/$MWProjectName.xcarchive" -configuration "$MWConfiguration" archive

archive succeeded, but cause Java Error !  like this:

• • ARCHIVE SUCCEEDED **

FATAL: Could not initialize class hudson.util.ProcessTree$UnixReflection java.lang.NoClassDefFoundError: Could not initialize class hudson.util.ProcessTree$UnixReflection at hudson.util.ProcessTree$UnixProcess.kill(ProcessTree.java:647) at hudson.util.ProcessTree$UnixProcess.killRecursively(ProcessTree.java:668) at hudson.util.ProcessTree$UnixProcess.killRecursively(ProcessTree.java:667) at hudson.util.ProcessTree$Unix.killAll(ProcessTree.java:589) at hudson.Launcher$LocalLauncher.kill(Launcher.java:949) at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:510) at hudson.model.Run.execute(Run.java:1724) at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43) at hudson.model.ResourceController.execute(ResourceController.java:97) at hudson.model.Executor.run(Executor.java:421)

If I excute the shell do not contain  archive , jenkens worked and not an error !
Finished: SUCCESS
 

What can I do to avoid this problem？