Pipeline builds fail when cleanWs() in post stage

Required context class hudson.FilePath is missing
Perhaps you forgot to surround the code with a step that provides this, such as: node
Error when executing cleanup post condition:
java.lang.IllegalArgumentException: Failed to prepare cleanWs step
	at org.jenkinsci.plugins.workflow.cps.DSL.invokeDescribable(DSL.java:401)
	at org.jenkinsci.plugins.workflow.cps.DSL.invokeMethod(DSL.java:181)
	at org.jenkinsci.plugins.workflow.cps.CpsScript.invokeMethod(CpsScript.java:122)
	at sun.reflect.GeneratedMethodAccessor672.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)
	at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1213)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1022)
	at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:42)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
	at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:157)
	at org.kohsuke.groovy.sandbox.GroovyInterceptor.onMethodCall(GroovyInterceptor.java:23)
	at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onMethodCall(SandboxInterceptor.java:155)
	at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:155)
	at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:159)
	at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:129)
	at com.cloudbees.groovy.cps.sandbox.SandboxInvoker.methodCall(SandboxInvoker.java:17)
	at WorkflowScript.run(WorkflowScript:226)
	at org.jenkinsci.plugins.pipeline.modeldefinition.ModelInterpreter.delegateAndExecute(jar:file:/data/jenkins/plugins/pipeline-model-definition/WEB-INF/lib/pipeline-model-definition.jar!/org/jenkinsci/plugins/pipeline/modeldefinition/ModelInterpreter.groovy:133)
	at org.jenkinsci.plugins.pipeline.modeldefinition.ModelInterpreter.runPostConditions(jar:file:/data/jenkins/plugins/pipeline-model-definition/WEB-INF/lib/pipeline-model-definition.jar!/org/jenkinsci/plugins/pipeline/modeldefinition/ModelInterpreter.groovy:757)
	at org.jenkinsci.plugins.pipeline.modeldefinition.ModelInterpreter.catchRequiredContextForNode(jar:file:/data/jenkins/plugins/pipeline-model-definition/WEB-INF/lib/pipeline-model-definition.jar!/org/jenkinsci/plugins/pipeline/modeldefinition/ModelInterpreter.groovy:402)
	at org.jenkinsci.plugins.pipeline.modeldefinition.ModelInterpreter.catchRequiredContextForNode(jar:file:/data/jenkins/plugins/pipeline-model-definition/WEB-INF/lib/pipeline-model-definition.jar!/org/jenkinsci/plugins/pipeline/modeldefinition/ModelInterpreter.groovy:400)
	at org.jenkinsci.plugins.pipeline.modeldefinition.ModelInterpreter.runPostConditions(jar:file:/data/jenkins/plugins/pipeline-model-definition/WEB-INF/lib/pipeline-model-definition.jar!/org/jenkinsci/plugins/pipeline/modeldefinition/ModelInterpreter.groovy:756)
	at com.cloudbees.groovy.cps.CpsDefaultGroovyMethods.each(CpsDefaultGroovyMethods:2030)
	at com.cloudbees.groovy.cps.CpsDefaultGroovyMethods.each(CpsDefaultGroovyMethods:2015)
	at com.cloudbees.groovy.cps.CpsDefaultGroovyMethods.each(CpsDefaultGroovyMethods:2056)
	at org.jenkinsci.plugins.pipeline.modeldefinition.ModelInterpreter.runPostConditions(jar:file:/data/jenkins/plugins/pipeline-model-definition/WEB-INF/lib/pipeline-model-definition.jar!/org/jenkinsci/plugins/pipeline/modeldefinition/ModelInterpreter.groovy:751)
	at org.jenkinsci.plugins.pipeline.modeldefinition.ModelInterpreter.executePostBuild(jar:file:/data/jenkins/plugins/pipeline-model-definition/WEB-INF/lib/pipeline-model-definition.jar!/org/jenkinsci/plugins/pipeline/modeldefinition/ModelInterpreter.groovy:728)
	at ___cps.transform___(Native Method)
	at com.cloudbees.groovy.cps.impl.ContinuationGroup.methodCall(ContinuationGroup.java:57)
	at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.dispatchOrArg(FunctionCallBlock.java:109)
	at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.fixName(FunctionCallBlock.java:77)
	at sun.reflect.GeneratedMethodAccessor319.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at com.cloudbees.groovy.cps.impl.ContinuationPtr$ContinuationImpl.receive(ContinuationPtr.java:72)
	at com.cloudbees.groovy.cps.impl.ConstantBlock.eval(ConstantBlock.java:21)
	at com.cloudbees.groovy.cps.Next.step(Next.java:83)
	at com.cloudbees.groovy.cps.Continuable$1.call(Continuable.java:174)
	at com.cloudbees.groovy.cps.Continuable$1.call(Continuable.java:163)
	at org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.use(GroovyCategorySupport.java:129)
	at org.codehaus.groovy.runtime.GroovyCategorySupport.use(GroovyCategorySupport.java:268)
	at com.cloudbees.groovy.cps.Continuable.run0(Continuable.java:163)
	at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.access$101(SandboxContinuable.java:34)
	at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.lambda$run0$0(SandboxContinuable.java:59)
	at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.GroovySandbox.runInSandbox(GroovySandbox.java:108)
	at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.run0(SandboxContinuable.java:58)
	at org.jenkinsci.plugins.workflow.cps.CpsThread.runNextChunk(CpsThread.java:182)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:332)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$200(CpsThreadGroup.java:83)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:244)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:232)
	at org.jenkinsci.plugins.workflow.cps.CpsVmExecutorService$2.call(CpsVmExecutorService.java:64)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at hudson.remoting.SingleLaneExecutorService$1.run(SingleLaneExecutorService.java:131)
	at jenkins.util.ContextResettingExecutorService$1.run(ContextResettingExecutorService.java:28)
	at jenkins.security.ImpersonatingExecutorService$1.run(ImpersonatingExecutorService.java:59)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
Caused by: org.codehaus.groovy.runtime.InvokerInvocationException: org.jenkinsci.plugins.workflow.steps.MissingContextVariableException: Required context class hudson.FilePath is missing
	at org.jenkinsci.plugins.workflow.cps.CpsStepContext.replay(CpsStepContext.java:499)
	at org.jenkinsci.plugins.workflow.cps.DSL.invokeStep(DSL.java:299)
	at org.jenkinsci.plugins.workflow.cps.DSL.invokeStep(DSL.java:209)
	at org.jenkinsci.plugins.workflow.cps.DSL.invokeDescribable(DSL.java:399)
	at org.jenkinsci.plugins.workflow.cps.DSL.invokeMethod(DSL.java:181)
	at org.jenkinsci.plugins.workflow.cps.CpsScript.invokeMethod(CpsScript.java:122)
	at sun.reflect.GeneratedMethodAccessor672.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)
	at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1213)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1022)
	at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:42)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
	at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:157)
	at org.kohsuke.groovy.sandbox.GroovyInterceptor.onMethodCall(GroovyInterceptor.java:23)
	at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onMethodCall(SandboxInterceptor.java:155)
	at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:155)
	at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:159)
	at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:129)
	at com.cloudbees.groovy.cps.sandbox.SandboxInvoker.methodCall(SandboxInvoker.java:17)
	... 33 more
Caused by: org.jenkinsci.plugins.workflow.steps.MissingContextVariableException: Required context class hudson.FilePath is missing
	at org.jenkinsci.plugins.workflow.steps.StepDescriptor.checkContextAvailability(StepDescriptor.java:260)
	at org.jenkinsci.plugins.workflow.cps.DSL.invokeStep(DSL.java:262)
	... 54 more 

pipeline {
  agent any
  stages {
    stage('Test') {
      steps {
        echo 'test'
      }
    }
  }
  post {
    always {
      cleanWs()
    }
  }
}