422
checkout.invalid_brandingcheckoutRule C10The checkout branding is not valid
Branding is validated field by field: display_name at most 60 characters, primary_color a six-digit hex colour, terms_url an https URL, and logo_file_id an available file whose purpose is checkout.logo.
Why the API refuses
WHEN the checkout branding is set, THE SYSTEM SHALL reject a display_name longer than 60 characters, a primary_color that is not a six-digit hex colour, a terms_url that is not https, and a logo_file_id that is not an available file of purpose checkout.logo, naming the offending field.
What to do
Read errors[].field. Three-digit hex (#0f7) and a named colour are both refused — send #0f766e. The logo must be uploaded with the right purpose first; a file uploaded for KYC cannot be reused as a logo.