CDN storage requires the CDN premium plugin
storage-server-policy returned 503 CDN storage requires the CDN premium plugin. when CDN storage is used without the plugin entitlement.
Why this happens
CDN server is selected but the CDN premium plugin is missing or disabled. Distinct from CDN object storage is not configured (creds/bucket missing).
Diagnose and fix
1. Install/enable the CDN premium plugin for this deployment.
2. Complete CDN credentials after the plugin is active (CDN credentials and test connection).
3. Retry the storage operation.
4. See Add a CDN server (providers overview) and Storage.