login Facebook registerCallback not called

Here is checklist to check whether your Facebook Sdk setup is correct:-

1. Check your manifest if you have setup Facebook initialization properly.

   <meta-data android:name="com.facebook.sdk.ApplicationId"
       android:value="@string/facebook_app_id" />
   
   <activity android:name="com.facebook.FacebookActivity"
       android:configChanges=
               "keyboard|keyboardHidden|screenLayout|screenSize|orientation"
       android:label="@string/app_name" />
   <activity
       android:name="com.facebook.CustomTabActivity"
       android:exported="true">
       <intent-filter>
           <action android:name="android.intent.action.VIEW" />
           <category android:name="android.intent.category.DEFAULT" />
           <category android:name="android.intent.category.BROWSABLE" />
           <data android:scheme="@string/fb_login_protocol_scheme" />
       </intent-filter>
   </activity>
   

2. Create Facebook CallBackManager variable

   var fbCallManager = CallbackManager.Factory.create()
   

3. On Click of Login with Facebook button. Put your required permission in Array.

     LoginManager.getInstance()
       .logInWithReadPermissions(this, Arrays.asList("public_profile", "email", "user_friends"))
     LoginManager.getInstance().registerCallback(fbCallManager, object : FacebookCallback<LoginResult> {
       override fun onSuccess(result: LoginResult?) {
          //login success
       }
   
       override fun onCancel() {
           //login cancelled by user
   
       }
   
       override fun onError(error: FacebookException?) {
           //login error handle exception
       }
   
   })
   

   }

4. Add callback result in onActivityResult method

   override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
       super.onActivityResult(requestCode, resultCode, data)
       fbCallManager.onActivityResult(requestCode, resultCode, data)
   }
   

5. Provide the Development and Release Key Hashes for Your

   keytool -exportcert -alias androiddebugkey -keystore "C:\Users\USERNAME.android\debug.keystore" | "PATH_TO_OPENSSL_LIBRARY\bin\openssl" sha1 -binary | "PATH_TO_OPENSSL_LIBRARY\bin\openssl" base64

Download openssl from here

6. Setup your Keyhash and Launcher activity in Facebook developer console.

References : Facebook

Missing this on my activity:

   @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        callbackManager.onActivityResult(requestCode, resultCode, data);
    }