Error 401 - Provided API key is not valid

I have an application which has been in use for over a year now. It started reporting the following error last week. The URI I am using is:

https://aeroapi.flightaware.com/aeroapi/airports/KCDC/flights/scheduled_arrivals

Any ideas?

{“title”: “Invalid API key”, “reason”: “INVALID_API_KEY”, “detail”: “Provided API key is not valid”, “status”: 401}

This request was closed and merged into request #622493aeroapi.flightaware.com returns …”.

Please re-open. The link you have posted for #622493 is broken.