I have added two API's both with Places, Geocoding & Geolocation enabled. The first API is restricted to the domain name for both https:// and http:// requests and the second server side API is unrestricted (See Screenshot: hidden link). However, I keep getting the following error when I try to Check API: hidden link
I have also tried leaving the restricted key unrestricted and it still gave the same error.
Is there any reason for this error and how can I fix it?
The error OVER_QUERY_LIMIT points to a problem with too many requests per second, but I suspect it may be a red herring.
In your screenshot you show that you are restricting the APIs that the key can call, and you are missing the Maps JavaScript API, for example.
I suggest you remove the API restrictions from your keys and re-test. If the error reported disappears then you can re-apply API restrictions but you'll need to include additional APIs, which may involve some trial and error.
After a lot of trial and error - I figured out that I needed to add a billing account to each of the API's and that was what was causing the issue. They are both working perfectly now.