Errors return JSON {errorJson}
Reseller API docs string reseller.api.docsErrorsNote — informational note that failed calls return JSON shaped like { "error": "…" } (placeholder {errorJson} in the locale).
Why this happens
Not a runtime failure by itself — documentation/help text on the Reseller API panel so integrators know how errors are encoded.
Diagnose and fix
1. When an API call fails, read the JSON error field (and HTTP status).
2. Map that message to the matching Help article when it is a product string.
3. Ensure your client parses JSON error bodies, not only status codes.
4. See Reseller API and Reseller API key (member).