In https://github.com/jenkinsci/junit-plugin/blob/master/src/main/java/hudson/tasks/test/DefaultTestResultParserImpl.java#L79 a Run instance (typically AbstractBuild), and additionally a Launcher are passed into a MasterToSlaveFileCallable. AFAIU, for this to work, they needed to be serializable in a Master/Slave scenario, alas, they are not.

The Run is actually not needed in the closure, so this can be fixed easily.

See JENKINS-34334 for a similar problem with a not serializable AbstractBuild instance, unrelated to DefaultTestResultParserImpl.