I know the country had been named Czech Republic but it has been changed to Czechia recently. The name seems to have failed to gain popularity around the world so far, though (you can easily find some related articles on the web).
When I talk with Czech citizens however, which one should I use? It might be better to use Czechia as it may make a good impression on them, but I also wonder if there are some citizens who opposed to the change, and these people might get dissatisfied if I say Czechia.