Whenever we need to restart tomcat hudson comes with a series of class not found exceptions when starting a maven job. Either hudson.EnvVars or hudson.Main - the classes are definetly in the classpach (checked WEB-INF/lib/hudson-core). After a number of restarts of tomcat (3-10) it sometimes works again.

FATAL: Could not initialize class hudson.EnvVars
java.lang.NoClassDefFoundError: Could not initialize class hudson.EnvVars
at hudson.model.Computer.getEnvironment(Computer.java:736)
at hudson.model.Run.getEnvironment(Run.java:1648)
at hudson.model.AbstractBuild.getEnvironment(AbstractBuild.java:663)
at hudson.maven.MavenModuleSetBuild.getEnvironment(MavenModuleSetBuild.java:128)
at hudson.maven.MavenModuleSetBuild$RunnerImpl.doRun(MavenModuleSetBuild.java:384)
at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:416)
at hudson.model.Run.run(Run.java:1243)
at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:304)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:122)

OR

FATAL: hudson/Main (wrong name: Main)
java.lang.NoClassDefFoundError: hudson/Main (wrong name: Main)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1302)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1233)
at hudson.EnvVars.initMaster(EnvVars.java:223)
at hudson.EnvVars.<clinit>(EnvVars.java:218)
at hudson.model.Computer.getEnvironment(Computer.java:736)
at hudson.model.Run.getEnvironment(Run.java:1648)
at hudson.model.AbstractBuild.getEnvironment(AbstractBuild.java:663)
at hudson.maven.MavenModuleSetBuild.getEnvironment(MavenModuleSetBuild.java:128)
at hudson.maven.MavenModuleSetBuild$RunnerImpl.doRun(MavenModuleSetBuild.java:384)
at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:416)
at hudson.model.Run.run(Run.java:1243)
at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:304)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:122)