Issue

A pipeline always ends with a java.io.NotSerializableException, even if the result is the expected one.

Environment

• CloudBees CI (CloudBees Core) on modern cloud platforms - Managed controller
• CloudBees CI (CloudBees Core) on traditional platforms - Client controller
• CloudBees Jenkins Enterprise - Managed controller
• CloudBees Jenkins Platform - Client controller
• CloudBees Jenkins Distribution
• Jenkins LTS

Resolution

By design a pipeline can only keep records of Serializable objects.
If you still need to keep an intermediate variable with a non serializable object, you need to extract it into a method and annotate this method with @NonCPS.
For example, you need to transform

def job = Jenkins.instance.getItemByFullName('test')
def sourceBuild = job.getLastBuild().getNumber()

into

@NonCPS
def getBuildNumber(String jobName) {
  def job = Jenkins.instance.getItemByFullName(jobName)
  return  job.getLastBuild().getNumber()
}

def build = getBuildNumber('test')

References