- title: "External Pipeline Validation Service Code Changes"
  removal_date: "2021-06-22"
  removal_milestone: "14.0"
  reporter: jreporter
  breaking_change: true
  body: |
    For self-managed instances using the experimental [external pipeline validation service](https://docs.gitlab.com/ee/administration/external_pipeline_validation.html), the range of error codes GitLab accepts will be reduced. Currently, pipelines are invalidated when the validation service returns a response code from `400` to `499`. In GitLab 14.0 and later, pipelines will be invalidated for the `406: Not Accepted` response code only.