When trying to build a small local test project, it failed giving me a ClassNotFoundException: hudson.remoting.Launcher.

I eventually figured out the problem:
Jetty unpacks the files of the war in a temporary file under my profile folder in windows. Unfortunately I had a norwegian username with the norwegian letter "å", and this was not handled correctly with the remoting-2.52.jar dependency. (The other dependencies seemed to be fine)

Changing my username, folder name and a registry key fixed the problem for me.

This is the output I got when trying to build a small testproject:

Started by user anonymous
Building in workspace C:\Users\Håvard\.jenkins\jobs\CI\workspace
> git.exe rev-parse --is-inside-work-tree # timeout=10
Fetching changes from the remote Git repository
> git.exe config remote.origin.url file:///F:/Kurs%20fasit/git # timeout=10
Fetching upstream changes from file:///F:/Kurs fasit/git
> git.exe --version # timeout=10
> git.exe -c core.askpass=true fetch --tags --progress file:///F:/Kurs fasit/git +refs/heads/:refs/remotes/origin/
> git.exe rev-parse "refs/remotes/origin/master^

" # timeout=10
Checking out Revision f9878edebfb6ed3530d875098b72759d69744ef8 (refs/remotes/origin/master)
> git.exe config core.sparsecheckout # timeout=10
> git.exe checkout -f f9878edebfb6ed3530d875098b72759d69744ef8
> git.exe rev-list f9878edebfb6ed3530d875098b72759d69744ef8 # timeout=10
Parsing POMs
Established TCP socket on 13308
[CI-parent] $ "C:\Program Files\Java\jdk1.8.0_66/bin/java" cp C:\Users\Håvard\.jenkins\plugins\maven-plugin\WEB-INF\lib\maven32-agent-1.7.jar;F:\apache-maven-3.2.5\boot\plexus-classworlds-2.5.2.jar;F:\apache-maven-3.2.5/conf/logging jenkins.maven3.agent.Maven32Main F:\apache-maven-3.2.5 C:\Users\H?vard\AppData\Local\Temp\jetty-0.0.0.0-8080-jenkins.war_jenkins-any-3884816799918590233.dir\webapp\WEB-INF\lib\remoting-2.52.jar C:\Users\Håvard\.jenkins\plugins\maven-plugin\WEB-INF\lib\maven32-interceptor-1.7.jar C:\Users\Håvard\.jenkins\plugins\maven-plugin\WEB-INF\lib\maven3-interceptor-commons-1.7.jar 13308
Exception in thread "main" java.lang.ClassNotFoundException: hudson.remoting.Launcher
at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:50)
at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass(ClassRealm.java:271)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:247)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:239)
at jenkins.maven3.agent.Maven32Main.main(Maven32Main.java:143)
at jenkins.maven3.agent.Maven32Main.main(Maven32Main.java:74)
ERROR: JENKINS-18403 JDK 5 not supported to run Maven; retrying with slave Java and setting compile/test properties to point to C:\Program Files\Java\jdk1.8.0_66
Established TCP socket on 13310
[CI-parent] $ "C:\Program Files\Java\jre1.8.0_66/bin/java" cp C:\Users\Håvard\.jenkins\plugins\maven-plugin\WEB-INF\lib\maven32-agent-1.7.jar;F:\apache-maven-3.2.5\boot\plexus-classworlds-2.5.2.jar;F:\apache-maven-3.2.5/conf/logging jenkins.maven3.agent.Maven32Main F:\apache-maven-3.2.5 C:\Users\H?vard\AppData\Local\Temp\jetty-0.0.0.0-8080-jenkins.war_jenkins-any-3884816799918590233.dir\webapp\WEB-INF\lib\remoting-2.52.jar C:\Users\Håvard\.jenkins\plugins\maven-plugin\WEB-INF\lib\maven32-interceptor-1.7.jar C:\Users\Håvard\.jenkins\plugins\maven-plugin\WEB-INF\lib\maven3-interceptor-commons-1.7.jar 13310
Exception in thread "main" java.lang.ClassNotFoundException: hudson.remoting.Launcher
at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:50)
at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass(ClassRealm.java:271)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:247)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:239)
at jenkins.maven3.agent.Maven32Main.main(Maven32Main.java:143)
at jenkins.maven3.agent.Maven32Main.main(Maven32Main.java:74)
ERROR: Failed to parse POMs
java.net.SocketException: Connection reset
at java.net.SocketInputStream.read(Unknown Source)
at java.net.SocketInputStream.read(Unknown Source)
at java.io.FilterInputStream.read(Unknown Source)
at java.io.BufferedInputStream.fill(Unknown Source)
at java.io.BufferedInputStream.read(Unknown Source)
at hudson.remoting.ChannelBuilder.negotiate(ChannelBuilder.java:331)
at hudson.remoting.ChannelBuilder.build(ChannelBuilder.java:282)
at hudson.slaves.Channels.forProcess(Channels.java:115)
at hudson.maven.AbstractMavenProcessFactory.newProcess(AbstractMavenProcessFactory.java:297)
at hudson.maven.ProcessCache.get(ProcessCache.java:236)
at hudson.maven.MavenModuleSetBuild$MavenModuleSetBuildExecution.doRun(MavenModuleSetBuild.java:778)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:537)
at hudson.model.Run.execute(Run.java:1741)
at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:531)
at hudson.model.ResourceController.execute(ResourceController.java:98)
at hudson.model.Executor.run(Executor.java:410)
Finished: FAILURE