CHW-5404 BillingPlanFeatureLookupFailed

unable to check plan feature flags; retry shortly

Default message: unable to check plan feature flags; retry shortly
HTTP status: 500 (server)

Problem. A plan-gated endpoint returned 500 before reaching the feature-check. Cause. The requirePlanFeature lookup of pricing_plans.features failed at the DB layer. Fix. Retry; logged with the feature key. HTTP 500.