Hi Selcuk,
Thank you for getting back to us.
I would like to inform you that the order_id is not strictly required for all enhanced conversions. While it helps with attribution, it's not mandatory in every scenario. Kindly refer to the document
Implement Enhanced Conversions for Web to get more information.
The error message you are getting indicates that the API is still expecting an order_id, even though it is optional for some conversion types. In your code, modify the logic for setting the order_id field. Only populate it if you have a valid order ID. If not, leave it empty.
I hope this helps. Kindly get back to us if you have any further queries.
This message is in relation to case "ref:!00D1U01174p.!5004Q02rzYg7:ref" (ADR-00225371)