⚠️ Experimental endpoint — not yet a stable contract. This action ships as experimental / beta. While experimental, its schema and behaviour may change without a version bump — including breaking changes within v1.0 itself. Anyone consuming it does so for evaluation only, or by coordinating adoption with their account manager so changes can be sequenced with them. It graduates to a stable, version-locked contract (where the normal breaking-change rules apply) only when this experimental notice is removed.

Set the applicable custom field values of a payment terminal without changing any other payment terminal properties. This action requires permission to view the payment terminal and the PaymentTerminals.update-custom-fields permission.

When custom fields are enabled for payment terminals, the customFields object may be empty; an empty object succeeds as a no-op without creating a value audit. Omitted identifiers remain unchanged, while an explicit null clears the corresponding value. If custom fields are disabled for the tenant or for payment terminals, an empty object returns a 422 error keyed as customFields, while a populated object returns errors keyed as customFields.<identifier>. Every submitted identifier is validated against the payment terminal, the current custom field configuration and the acting administrator's access. Unknown or inapplicable identifiers also return a 422 error keyed as customFields.<identifier>, and no submitted values are changed.