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Knative

knative-v1.21.0Orchestration & Management
Jan 27, 2026

CHECK 3OTHER 16

Knative v1.21.0 is an operator-facing release with changes to compatibility, metrics, feature behavior, and defects. The broader release also contains dependency housekeeping, so the listed operational changes are most relevant to users managing metrics or cross-service traffic routing.

Check if affected (3)

  • breakingServing invocation duration metric rename

    Applies if you use the kn.queueproxy.app.duration metric.

    The metric kn.queueproxy.app.duration is renamed to kn.serving.invocation.duration in Knative v1.21.0.

  • breakingServing queue depth metric rename

    Applies if you use the kn.queueproxy.depth metric.

    The metric kn.queueproxy.depth is renamed to kn.serving.queue.depth in Knative v1.21.0.

  • breakingService revision ownership validation

    Applies if your Services route traffic to revisions belonging to different services.

    In Knative v1.21.0, Services can no longer route traffic to revisions owned by different services. Such an attempt sets Ready=False with reason RevisionNotOwned.

All 16 other recorded changesfixes 8 · constraints 5 · additions 3

fixes (8)

  • Preserve deployment and template annotations and labels during reconcile
  • Fall back to HTTP1 on failed HTTP2 health probes (e.g. on connection error or non-readiness)
  • Fix flaky HTTPS e2e tests by waiting for HTTPS endpoint to be Ready.
  • Fix request log output corruption when using invalid log templates
  • Fixed duplicate ACME challenge paths when Services with traffic tags use HTTP-01 challenges for TLS certificates.
  • Services with invalid networking.knative.dev/* annotations on the revision template now fail immediately with a clear error instead of getting stuck.
  • Switch to async metric instrumentation to avoid unbounded memory growth
  • fix sub-second precision metric reporting

constraints (5)

  • Add terminationGracePeriodSeconds support for user and sidecar container probes
  • Added support for OpenTelemetry W3C Trace Context (traceparent header) in request logging, while maintaining backward compatibility with Zipkin B3 format.
  • Allow activator to be out of the request path when system-internal-tls is enabled
  • Allow adjusting Revision min/max scale annotations
  • Allow unreachable revisions with initialScale > 1 to scale to 0

additions (3)

  • You can now set the new feature pod-is-always-schedulable to true in the config-deployment ConfigMap.
  • Activator probe timeout and frequency are now configurable via PROBE_TIMEOUT and PROBE_FREQUENCY environment variables.
  • Include two new activator metrics (kn.activator.stats.conn.reachable, kn.activator.stats.conn.errors)
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