The DHL Location Finder - Unified API is essentially built by taking a geolocation with latitude, and longitude coordinates as reference, and then analyzing what DHL locations are nearby. This is the process that the endpoint "find-by-geo" implements.
When using the endpoint "find-by-address", an additional step is added where we implement a geolocation service to find the coordinates of a given address. This service however has challenges in correctly identifying all possible postal codes in the world. When doing a call to the API with the find-by-address endpoint and adding a postal code that is not identifiable with our geolocation source, the API will return an empty response as below:
1{
2 "locations": []
3}
We are aware of this issue and we are working on a solution to improve our data quality and support a larger scale of postal codes worldwide. Please excuse the inconvenience.
In the meantime, we suggest you use the endpoint "find-by-geo" and directly input the coordinates of the address you wish to query. Please refer to the DHL Location Finder - Unified API documentation to read more about it.