I am getting this error. When I try to sign in with facebook to my app. When I first time authentication it will correctly working. After I unistalled my application and now
The issue for me (at the time of writing this) was when adding hash directly in Facebook Login -> Settings page. For some strange reason it does not save it correctly.
I fixed this with going to Quickstart and adding hashes in one of the steps and hitting Save. (fix will probably be obsolete when they fix their web page)
I did not have an issue with the tool, it generated correct hash. People with wrong Play store hashes probably have Play store signing enabled or entered wrong credentials.