@Rupnesh
Yes, I had this issue at the beginning too. Generating new key helped. But that is not my problem. I have different keys for debug version and for release version. Both are in facebook settings.
Also if I install release build (the same as from store) from link, the facebook login works perfectly. Only if app is download from store, it do not work. And key hashes are still the same. I checked it by this thread