Customer portal product swaps work with multiple matching selling plans
Subscribers using the customer portal to change their subscription product can now complete the swap even when the new product variant belongs to multiple selling plans with the same billing interval. Previously, that combination returned a hard error and left subscribers with no path forward.
What was happening
When a subscriber swapped a line in the customer portal — for example, switching to a different size or flavour — Subi looks up the correct selling plan for the new variant to keep the subscription's billing terms intact. If more than one selling plan with a matching interval covered that variant, Subi could not determine which plan to use and the request failed with an unrecoverable error.
How it is resolved
The selling plan resolution now applies two safe tie-breaking steps before failing:
- Prefer the subscriber's current plan. If the selling plan already on the subscription is among the candidates, Subi selects it. The subscriber keeps their existing billing terms and only the product changes.
- Pick deterministically when all candidates are equivalent. If every candidate plan shares the same interval and discount configuration, Subi selects the first one and the swap completes normally.
If neither condition can resolve the ambiguity, the request still returns an error — but that combination is no longer reachable in practice for the case that was failing in production.
Who is affected
Merchants whose product catalogue assigns a variant to more than one selling plan at the same frequency — which can happen naturally when products belong to several subscription groups — were exposed to this error. Subscribers on those stores can now change their subscribed product without hitting a dead end in the portal.