I wanted to update latest jenkins and plugins, but I am getting the following exception when checking out any project from our stash server via https.

I have checked the plugins folder, jsch is available in the following places:

_./scp/WEB-INF/lib/jsch-0.1.42.jar
./maven-plugin/WEB-INF/lib/jsch-0.1.44-1.jar
./ssh/WEB-INF/lib/jsch-0.1.42.jar
./git-changelog/WEB-INF/lib/jsch-0.1.53.jar
./git-client/WEB-INF/lib/jsch-0.1.50.jar
./cvs/WEB-INF/lib/jsch-0.1.50.jar
_
So you see jsch is available in git-client-plugin, but somehow it can not be loaded.
For us this is blocker, because we have to update to new versions due to another reason and are not able to.

hudson.plugins.git.GitException: Failed to fetch from https://stash.ourcompany.de/scm/project/repo.git
at hudson.plugins.git.GitSCM.fetchFrom(GitSCM.java:763)
at hudson.plugins.git.GitSCM.retrieveChanges(GitSCM.java:1012)
at hudson.plugins.git.GitSCM.checkout(GitSCM.java:1043)
at hudson.scm.SCM.checkout(SCM.java:485)
at hudson.model.AbstractProject.checkout(AbstractProject.java:1277)
at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:610)
at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:86)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:532)
at hudson.model.Run.execute(Run.java:1741)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:98)
at hudson.model.Executor.run(Executor.java:408)
Caused by: hudson.plugins.git.GitException: java.io.IOException: Remote call on diva-vtdivaci01-x failed
at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler.execute(RemoteGitImpl.java:172)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:94)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:619)
at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler.invoke(RemoteGitImpl.java:131)
at com.sun.proxy.$Proxy55.execute(Unknown Source)
at hudson.plugins.git.GitSCM.fetchFrom(GitSCM.java:761)
... 11 more
Caused by: java.io.IOException: Remote call on diva-vtdivaci01-x failed
at hudson.remoting.Channel.call(Channel.java:786)
at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler.execute(RemoteGitImpl.java:145)
... 18 more
Caused by: java.lang.ExceptionInInitializerError
at org.eclipse.jgit.api.FetchCommand.call(FetchCommand.java:120)
at org.jenkinsci.plugins.gitclient.JGitAPIImpl$2.execute(JGitAPIImpl.java:631)
at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler$1.call(RemoteGitImpl.java:152)
at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler$1.call(RemoteGitImpl.java:145)
at hudson.remoting.UserRequest.perform(UserRequest.java:118)
at hudson.remoting.UserRequest.perform(UserRequest.java:48)
at hudson.remoting.Request$2.run(Request.java:328)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:72)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at hudson.remoting.Engine$1$1.run(Engine.java:63)
at java.lang.Thread.run(Thread.java:745)
at ......remote call to diva-vtdivaci01-x(Native Method)
at hudson.remoting.Channel.attachCallSiteStackTrace(Channel.java:1413)
at hudson.remoting.UserResponse.retrieve(UserRequest.java:221)
at hudson.remoting.Channel.call(Channel.java:778)
... 19 more
Caused by: java.lang.RuntimeException: java.lang.ClassNotFoundException: com.jcraft.jsch.Buffer
at org.kohsuke.asm5.ClassWriter.getCommonSuperClass(ClassWriter.java:1684)
at org.kohsuke.asm5.ClassWriter.getMergedType(ClassWriter.java:1654)
at org.kohsuke.asm5.Frame.merge(Frame.java:1426)
at org.kohsuke.asm5.Frame.merge(Frame.java:1325)
at org.kohsuke.asm5.MethodWriter.visitMaxs(MethodWriter.java:1475)
at org.kohsuke.asm5.tree.MethodNode.accept(MethodNode.java:833)
at org.kohsuke.asm5.commons.JSRInlinerAdapter.visitEnd(JSRInlinerAdapter.java:187)
at org.kohsuke.asm5.MethodVisitor.visitEnd(MethodVisitor.java:877)
at org.kohsuke.asm5.ClassReader.readMethod(ClassReader.java:1021)
at org.kohsuke.asm5.ClassReader.accept(ClassReader.java:693)
at org.kohsuke.asm5.ClassReader.accept(ClassReader.java:506)
at org.jenkinsci.bytecode.Transformer.transform(Transformer.java:76)
at hudson.ClassicPluginStrategy$AntClassLoader2.defineClassFromData(ClassicPluginStrategy.java:800)
at jenkins.util.AntClassLoader.getClassFromStream(AntClassLoader.java:1310)
at jenkins.util.AntClassLoader.findClassInComponents(AntClassLoader.java:1366)
at jenkins.util.AntClassLoader.findClass(AntClassLoader.java:1326)
at jenkins.util.AntClassLoader.loadClass(AntClassLoader.java:1079)
at java.lang.ClassLoader.loadClass(ClassLoader.java:707)
at hudson.remoting.RemoteClassLoader$ClassLoaderProxy.fetch4(RemoteClassLoader.java:761)
at hudson.remoting.RemoteClassLoader$ClassLoaderProxy.fetch3(RemoteClassLoader.java:818)
at sun.reflect.GeneratedMethodAccessor129.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:619)
at hudson.remoting.RemoteInvocationHandler$RPCRequest.perform(RemoteInvocationHandler.java:608)
at hudson.remoting.Request$2.run(Request.java:326)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:68)
at jenkins.util.ContextResettingExecutorService$2.call(ContextResettingExecutorService.java:46)
at java.util.concurrent.FutureTask.run(FutureTask.java:273)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1176)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
at java.lang.Thread.run(Thread.java:795)