Google Maps not displaying

I have a problem with the Google Maps not showing on a site that’s been moved from staging > live. I get a Javascript error where the maps don’t display.

JQMIGRATE: Migrate is installed, version 1.4.1 Failed to load resource: the server responded with a status of 404 (Not Found) Google Maps API error: MissingKeyMapError @ Google Maps API warning: NoApiKeys @ Google Maps API warning: SensorNotRequired

I’ve added the Dashboard plugin to the site and activated it, but it isn’t recognised. Currently I’m viewing the site via a modified HOSTS file with the URL set to the correct IP.

What can I do to resolve the problem?