# istio_33734.yaml
apiVersion: release-notes/v2
kind: feature

area: traffic-management
issue: []

releaseNotes:
- |
  '**Improved** TCP probes now working as expected: When using TCP probes with older versions of istio the check was always successful, even if the application didn't open the port.'

upgradeNotes:
  - title: TCP probes now working as expected
    content: |
        When using TCP probes with older versions of istio the check was always successful, even if the application didn't open the port.
        This may cause problems when upgrading: If you had a missconfiguration in a TCP probe (e.g wrong port) you maybe haven't noticed.
        After the upgrade a missconfigured TCP probe will fail and therefore might cause downtimes.

docs:
- '[details] https://istio.io/latest/docs/ops/configuration/mesh/app-health-check/' # Not yet updated