I've checked this forum for the many occurances of this Google Maps annoyance, but none of the reported reasons seem to apply here:
- Hotspots 5.3.3 installed freshly on Joomla! 3.6.5 (de)
- new Google Maps API key created and entered into Hotspots configuration
- double checked, that the key has not been altered during copy and paste
Even on the backend (Hotspots dashboard and locations screens) Google Maps doesn't appear, but only its aforementioned error message shows up.
Since JQuery cannot be blamed on the backend - what else could possibly cause this problem?