We send to
https://my.prom.ua/api/v1/delivery/save_declaration_idarray
(
[order_id] => 163350514
[declaration_id] => 20450430675518
[delivery_type] => nova_poshta
)
We get the response {"status": "error", "message": "\u041d\u0435\u0438\u0437\u0432\u0435\u0441\u0442\u043d\u0430\u044f \u043e\u0448\u0438\u0431\u043a\u0430 ", "errors": null}
What is the translation of "Unknown error"
Contact prom.ua technical support with a question why such errors occur