billing_portal_unavailable
Stripe Billing Portal is unavailable. 503 means gateway/return-origin configuration is missing, the configuration is inactive or permits subscription editing, or required capabilities differ. Protected sessions also require explicit cancellation-disabled evidence and an explicit configuration ID; no default fallback. Manage billing requires payments and invoices, plus cancellation only for verified monthly terms. 502 means the configuration read or session creation failed, timed out, or returned incomplete evidence. The freshly verified configuration ID is pinned in the session. No guessed link is returned.
Problem shape
Every non-2xx response is an RFC 9457 application/problem+json body. The type URI below is stable and machine-matchable, so branch on the final path segment (the code) and treat the status as redundant confirmation. See the error-handling guide.
{
"type": "https://docs.vocapable.com/errors/billing_portal_unavailable",
"title": "…",
"status": "…",
"detail": "…",
"instance": "/v1/…"
}