422
fees.no_planfeesRule R1No fee plan is in force for this merchant
Pricing could not be resolved: the merchant has no accepted, active or superseded assignment covering the moment being priced, and the default_fee_plan_code setting is empty or names no plan with an active version.
Why the API refuses
WHEN Compute or GetAssignment is executed, THE SYSTEM SHALL select the tenant's assignment whose status is accepted, active or superseded and whose effective_from is at or before at and whose effective_to is absent or after at; IF no such assignment exists THEN THE SYSTEM SHALL fall back to the latest active version of the plan named by the tenant setting default_fee_plan_code; IF that setting is empty or names no plan with an active version THEN THE SYSTEM SHALL reject the query.
What to do
A platform configuration gap rather than an integration bug. Propose and have the merchant accept a plan, or set a default plan that has an active version. Note the time dimension: an assignment whose effective_from is in the future does not price today.