Caused by: java.lang.LinkageError: loader (instance of  hudson/remoting/RemoteClassLoader): attempted  duplicate class definition for name: "hudson/model/Descriptor"
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
	at hudson.remoting.RemoteClassLoader.loadClassFile(RemoteClassLoader.java:152)
	at hudson.remoting.RemoteClassLoader.findClass(RemoteClassLoader.java:131)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
	at java.lang.Class.getDeclaredFields0(Native Method)
	at java.lang.Class.privateGetDeclaredFields(Class.java:2308)
	at java.lang.Class.getDeclaredField(Class.java:1897)
	at java.io.ObjectStreamClass.getDeclaredSUID(ObjectStreamClass.java:1639)
	at java.io.ObjectStreamClass.access$700(ObjectStreamClass.java:69)
	at java.io.ObjectStreamClass$2.run(ObjectStreamClass.java:467)
	at java.io.ObjectStreamClass$2.run(ObjectStreamClass.java:455)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.io.ObjectStreamClass.<init>(ObjectStreamClass.java:455)
	at java.io.ObjectStreamClass.lookup(ObjectStreamClass.java:352)
	at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:589)
	at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1601)
	at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1514)
	at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1601)
	at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1514)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1750)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1347)
	at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1964)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1888)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1771)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1347)
	at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1964)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1888)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1771)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1347)
	at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1964)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1888)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1771)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1347)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:369)
	at hudson.remoting.UserRequest.deserialize(UserRequest.java:182)
	at hudson.remoting.UserRequest.perform(UserRequest.java:98)
	at hudson.remoting.UserRequest.perform(UserRequest.java:48)
	at hudson.remoting.Request$2.run(Request.java:326)
	at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:72)
	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
	at java.util.concurrent.FutureTask.run(FutureTask.java:166)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
	at java.lang.Thread.run(Thread.java:722)