Unable to add window -- token null is not valid; is your activity running?

[orafoxinc]

Process: com.example.android, PID: 10996 android.view.WindowManager$BadTokenException: Unable to add window -- token null is not valid; is your activity running? at android.view.ViewRootImpl.setView(ViewRootImpl.java:907) at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:387) at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:95) at android.app.Dialog.show(Dialog.java:342) at com.hbb20.CountryCodeDialog.openCountryCodeDialog(CountryCodeDialog.java:265) at com.hbb20.CountryCodePicker.launchCountrySelectionDialog(CountryCodePicker.java:2207) at com.hbb20.CountryCodePicker.launchCountrySelectionDialog(CountryCodePicker.java:2199) at com.hbb20.CountryCodePicker$1.onClick(CountryCodePicker.java:147) at android.view.View.performClick(View.java:7125) at android.view.View.performClickInternal(View.java:7102) at android.view.View.access$3500(View.java:801) at android.view.View$PerformClick.run(View.java:27336) at android.os.Handler.handleCallback(Handler.java:883) at android.os.Handler.dispatchMessage(Handler.java:100) at android.os.Looper.loop(Looper.java:214) at android.app.ActivityThread.main(ActivityThread.java:7356) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

We are use ViewPager with custom view without fragment