Getting unity facebook error while looging in

While logging in game is crashing in some mobile devices.

Any help is appreciated, thank you

Here is the logcat,

Caused by: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.dpc.zenra.Humpty/com.facebook.unity.FBUnityLoginActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2198)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257)
at android.app.ActivityThread.access$800(ActivityThread.java:139)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5086)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.facebook.unity.FB.getKeyHash(FB.java:378)
at com.facebook.unity.FBLogin.login(FBLogin.java:92)
at com.facebook.unity.FBLogin.loginWithReadPermissions(FBLogin.java:42)
at com.facebook.unity.FBUnityLoginActivity.onCreate(FBUnityLoginActivity.java:40)
at android.app.Activity.performCreate(Activity.java:5248)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1110)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2162)

There is an open issue in Github repo of the facebook sdk

Here is the link: