Symptom

READY=False, REASON=SourceNotReady. Transient: the controller requeues and clears the condition once the source publishes.

Cause

A stage’s sourceRef resolved to an ExternalArtifact (directly, or via a producer’s RFC-0012 back-pointer such as a JaaS JsonnetSnippet), but that artifact’s status.conditions[Ready] is not yet True — its producer has not finished publishing a revision. The StageSet gates on Ready=True so it never builds against a half-written artifact.

Diagnosis

# Which artifact, and is it Ready?
kubectl get externalartifact -n <namespace>
kubectl describe externalartifact <name> -n <namespace>

# If the producer is a JsonnetSnippet (or other producer kind), check it:
kubectl describe jsonnetsnippet <name> -n <namespace>

Remediation

This usually clears on its own when the producer publishes. If it persists:

• confirm the producing controller (e.g. the JaaS operator, or Flux source-controller) is running and reconciling the producer object;
• check the producer’s own Ready condition for an upstream error (a failed render, an unreachable GitRepository/OCIRepository source);
• once the producer reports Ready=True with a status.artifact, the StageSet converges on the next reconcile.

If the artifact never appears at all, the reason is ArtifactNotFound; a spec/API resolution failure is ResolveFailed. See stages and sources.