I came across very strange issue with the Facebook Key Hashes. The Facebook SDK is used in my Android App to provide the native authentication. Everything worked just fine, until today morning when made some temporary configuration changes. I removed the original Key Hash (keyhash1) and replace it with another one (keyhash2). After some testing, restored the configuration, but my original Key Hash keyhash1 stopped to work... The message says "keyhash1 does not match any stored key hashes".
I double checked everything, tried to rebuild the app many times, but this didn't succeed. After few hours of digging, found this answer. Since I can't delete this app (it is already used by many users), I decided to try reproduce this issue somewhere else. Prepared test app, added and removed the Key Hash few times and voila, issue successfully reproduced. Based on mentioned stackoverflow answer, removed the Facebook App, and created a new one using the same Key Hash, it started to work again.
The question how can I fix the original application? Is that normal that Facebook blocked the Key Hashes?