How to Mark a Build Unstable With warnError in Jenkins

warnError runs a block and, on failure, logs a message and sets the build result to UNSTABLE rather than FAILURE.

Use warnError('message') { ... } so a flaky or advisory step turns the build yellow (UNSTABLE) instead of red. The pipeline keeps going and the message lands in the log.

Steps

• Identify a step whose failure should warn, not block.
• Wrap it in warnError('reason') { }.
• Distinguish UNSTABLE from FAILURE in your downstream gating.

Jenkinsfile

pipeline {
  agent any
  stages {
    stage('Lint') {
      steps {
        warnError('Lint reported issues') {
          sh 'npm run lint'
        }
      }
    }
  }
  post {
    unstable { echo 'Build is unstable: review the lint output.' }
  }
}

Gotchas

• warnError always sets UNSTABLE; use catchError if you need a different result.
• An UNSTABLE result still counts as a non-success in many downstream checks.

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