Google Geocoding stopped to work for Crimea, Ukraine
Google (reverse) geocoding service stopped working for Crimea due to territorial dispute.
A not-trivial, but future-proof technical solution is to create an abstraction API over geocoding services rather than using a specific service directly in your app.
This way you reduce dependency on a specific service.
For example, you can use Yandex geocoding service if the coordinates are within the bounding rectangle of Crimea:
http://geocode-maps.yandex.ru/1.x/?geocode=34.104996,44.957844&lang=en-US
Another benefit of an abstraction level is that you may very quickly switch to a different service if your "main" service goes down (for whatever reason).
Please note that support of certain regions or countries by a software product may be subject to US / EU sanctions. Support of any region with a territorial dispute is a potential problem.
Yes, it's a restriction due to political events. I got this answer from Google Support:
Since Crimea currently is a disputed territory (http://en.wikipedia.org/wiki/List_of_territorial_disputes), Geocoder results will currently not return results for reverse geocoding.