We recently converted our Windows slaves from using JNLP service to being logged in via ssh. At that time, several of our CTest-running jobs started failing with the stack trace attached. Note the reference to "/var/lib/jenkins/userContent/xunit/CTest" in the output - that path clearly doesn't exist on our Windows slaves. I don't know that that is the cause of the problem, of course, but it seems potentially relevant. Perhaps the xUnit plugin is somehow assuming that the remote side is Unix since it is logged into via ssh?

[xUnit] [INFO] - Starting to record.
[xUnit] [INFO] - Processing CTest-Version N/A (default)
[xUnit] [INFO] - [CTest-Version N/A (default)] - 1 test report file(s) were found with the pattern 'build/memcached/Testing/**/Test.xml' relative to 'C:\Jenkins\workspace\memcached-gerrit-master\label_exp\watson-windows' for the testing framework 'CTest-Version N/A (default)'.
[xUnit] [INFO] - Converting 'C:\Jenkins\workspace\memcached-gerrit-master\label_exp\watson-windows\build\memcached\Testing\20160112-0155\Test.xml' .
[xUnit] [ERROR] - Conversion error remote file operation failed: /var/lib/jenkins/userContent/xunit/CTest at hudson.remoting.Channel@b07fd3:channel
ERROR: Publisher org.jenkinsci.plugins.xunit.XUnitPublisher aborted due to exception
java.io.IOException: remote file operation failed: C:\Jenkins\workspace\memcached-gerrit-master\label_exp\watson-windows at hudson.remoting.Channel@34a40002:watson-windows-01
at hudson.FilePath.act(FilePath.java:910)
at hudson.FilePath.act(FilePath.java:887)
at org.jenkinsci.plugins.xunit.XUnitProcessor.performTests(XUnitProcessor.java:138)
at org.jenkinsci.plugins.xunit.XUnitProcessor.performXUnit(XUnitProcessor.java:81)
at org.jenkinsci.plugins.xunit.XUnitPublisher.perform(XUnitPublisher.java:112)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:804)
at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:776)
at hudson.model.Build$BuildExecution.post2(Build.java:183)
at hudson.model.AbstractBuild$AbstractBuildExecution.post(AbstractBuild.java:725)
at hudson.model.Run.execute(Run.java:1701)
at hudson.matrix.MatrixRun.run(MatrixRun.java:146)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:231)
Caused by: hudson.util.IOException2: There are some problems during the conversion into JUnit reports:
at org.jenkinsci.plugins.xunit.service.XUnitTransformer.invoke(XUnitTransformer.java:181)
at org.jenkinsci.plugins.xunit.service.XUnitTransformer.invoke(XUnitTransformer.java:42)
at hudson.FilePath$FileCallableWrapper.call(FilePath.java:2461)
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$1.call(InterceptingExecutorService.java:72)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: org.jenkinsci.plugins.xunit.exception.XUnitException: Conversion error remote file operation failed: /var/lib/jenkins/userContent/xunit/CTest at hudson.remoting.Channel@b07fd3:channel
at org.jenkinsci.plugins.xunit.service.XUnitConversionService.convert(XUnitConversionService.java:91)
at org.jenkinsci.plugins.xunit.service.XUnitTransformer.invoke(XUnitTransformer.java:144)
... 10 more
Caused by: java.io.IOException: remote file operation failed: /var/lib/jenkins/userContent/xunit/CTest at hudson.remoting.Channel@b07fd3:channel
at hudson.FilePath.act(FilePath.java:910)
at hudson.FilePath.act(FilePath.java:887)
at hudson.FilePath.exists(FilePath.java:1319)
at org.jenkinsci.plugins.xunit.service.XUnitConversionService.convertInputMetricXSL(XUnitConversionService.java:106)
at org.jenkinsci.plugins.xunit.service.XUnitConversionService.convert(XUnitConversionService.java:80)
... 11 more
Caused by: java.io.IOException: Remote call on channel failed
at hudson.remoting.Channel.call(Channel.java:731)
at hudson.FilePath.act(FilePath.java:903)
... 15 more
Caused by: java.lang.NoClassDefFoundError: hudson/remoting/RemoteClassLoader$RemoteIClassLoader
at hudson.remoting.RemoteClassLoader.export(RemoteClassLoader.java:656)
at hudson.remoting.UserRequest.<init>(UserRequest.java:69)
at hudson.remoting.Channel.call(Channel.java:721)
... 16 more