Symptom

READY=False, REASON=ResolveFailed. The Message describes why resolution failed.

Cause

A stage’s sourceRef could not be resolved to an ExternalArtifact for a spec/config or API reason (distinct from “not published yet”, which is SourceNotReady, and “no such object”, which is ArtifactNotFound). Common cases:

• an ambiguous producer — more than one ExternalArtifact back-points at the same producer object, so the target is undefined;
• a cross-namespace ref rejected by --no-cross-namespace-refs;
• an API error reading the source or artifact (RBAC denial, the artifact CRD not installed).

When the failing sourceRef targets another namespace, the Message is deliberately scrubbed to cross-namespace <kind> %q is not reachable so tenants cannot fingerprint other namespaces — check that source CR’s status in its own namespace.

Diagnosis

kubectl describe stageset <name> -n <namespace>
# Ambiguity: are there multiple artifacts pointing at the producer?
kubectl get externalartifact -n <namespace> -o yaml | grep -A3 sourceRef

Remediation

• Ambiguous producer: ensure exactly one ExternalArtifact back-points at the producer, or reference the ExternalArtifact directly by name.
• Cross-namespace rejected: move the source into the StageSet’s namespace, or run the controller without --no-cross-namespace-refs if your tenancy model allows it.
• RBAC / missing CRD: grant the controller (or the impersonated serviceAccountName) read on the source kind, or install the source-controller CRDs.