If the maps are not working in All-In-One WP Nearby Places, make sure you have created a valid API and enabled the required API libraries. Also make sure you have added the correct website URL if you restricted access to the API.

More information will be added here in future to cover scenarios where the map is not working.

Also please visit this link for list of error messages:

https://developers.google.com/maps/documentation/javascript/error-messages