Unable to add window -- token android.os.BinderProxy is not valid; is your activity running?

I was seeing this error reported once in a while from some of my apps, and here's what solved it for me:

if(!((Activity) context).isFinishing())
{
    //show dialog
}

All the other answers out there seem to be doing weird things like iterating through the list of running activities, but this is much simpler and seems to do the trick.

This can occur when you are showing the dialog for a context that no longer exists. A common case - if the 'show dialog' operation is after an asynchronous operation, and during that operation the original activity (that is to be the parent of your dialog) is destroyed. For a good description, see this blog post and comments:

http://dimitar.me/android-displaying-dialogs-from-background-threads/

From the stack trace above, it appears that the facebook library spins off the auth operation asynchronously, and you have a Handler - Callback mechanism (onComplete called on a listener) that could easily create this scenario.

When I've seen this reported in my app, its pretty rare and matches the experience in the blog post. Something went wrong for the activity/it was destroyed during the work of the the AsyncTask. I don't know how your modification could result in this every time, but perhaps you are referencing an Activity as the context for the dialog that is always destroyed by the time your code executes?

Also, while I'm not sure if this is the best way to tell if your activity is running, see this answer for one method of doing so:

Check whether activity is active

one simple workaround is to catch the exception :

try {
        alertDialog.show()
    }
catch (WindowManager.BadTokenException e) {
        //use a log message
    }

It's not elegant but sometimes easy when you have to manage async operations and you are not sure wether activity is up or not when you want to show the dialog.