409
merchants.incompletemerchantsRule R9Onboarding is missing required information
Submission requires legal_name, registration_number and mcc, at least one person, an id document for that person, and a registration document. The response lists what is missing rather than failing on the first gap.
Why the API refuses
WHEN SubmitOnboarding is executed, THE SYSTEM SHALL reject it unless legal_name, registration_number and mcc are present, at least one person exists, that person has a document of type id, and a document of type registration exists, listing what is missing.
What to do
Read the list in detail/errors and collect all of it before resubmitting. Showing the merchant a progress checklist built from this response is a better experience than letting them submit and be refused.