** UPDATE **
This issue has been resolved since 15:00 GMT.
Dear valued customers,
We are currently experiencing some issues of slowness on the system and on the API responses.
This possible affects results from the API or 'internal server error' response.
We are aware of the situation and doing everything we can in order to resolve this matter asap.
We will keep you posted when this will be resolved.
For any other issues or related questions, do not hesitate to contact our support team at firstname.lastname@example.org