In case you face an error in Swagger when calling the data via shipper API, use this article to see the reason of the error.
Although Swagger shows the error code, the tool does not precisely describe the reason behind the error.
1. Open the browser console (F12) and go to the network tab;
2. Then try the same action again;
3. Click on the failing request entry;
4. Go to the "preview" bar;
5. There, you can see under preview section what was wrong in the call.
As it is described in the preview bar, the reason of the error here is the wrong auction ID.