How to fix On error Facebook log in result in android - facebook-login

Question

when I click on the button of sign in the window of choosing facebook profile appears ! but once I confirm the the profile the app crashes . And by using logs I figured out that the register call is not successful so I'have a facebook exeception which causes error , how can i find the source error ?
facebookSignInButton.setOnClickListener(View.OnClickListener {
// Login
Log.i(TAG,"CLICKED")
loginManager.logInWithReadPermissions(this, Arrays.asList("public_profile"))
Log.i(TAG,"Permissions")
loginManager.registerCallback(callbackManager,
object : FacebookCallback<LoginResult> {
override fun onSuccess(loginResult: LoginResult) {
Log.d(TAG, "Facebook token: " + loginResult.accessToken.token)
startActivity(Intent(applicationContext,MainActivity::class.java))
}
override fun onCancel() {
Log.i(TAG, "Facebook onCancel.")
}
override fun onError(error: FacebookException) {
Log.d(TAG, "Facebook onError.")
// This part is written in run console
}
})
})
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
super.onActivityResult(requestCode, resultCode, data)
callbackManager!!.onActivityResult(requestCode, resultCode, data)
Log.i(TAG,"RESULT"+resultCode.toString()) // this retrun -1
Log.i(TAG,"REQUEST"+requestCode.toString())
}
I expect starting a new activity while logging.

Answer 1

After printing the msg error the problem is in the hash key it doesn't match any key stored !
so instead if using line cmnds I just use this code in my on create function and then copy the hash key into your facebook developer app
val packageName = this.getApplicationContext().getPackageName()
val info : PackageInfo = getPackageManager().getPackageInfo(packageName, PackageManager.GET_SIGNATURES);
for ( signature in info.signatures) {
var md = MessageDigest.getInstance("SHA")
md.update(signature.toByteArray())
val hashKey = android.util.Base64.encodeToString(md.digest(), 0)
Log.i(TAG,"HADHKEEEY"+hashKey)
}
Log.i(TAG,"NAAAMEE"+packageName)