Contact webservice on application crash

Question

I want my Android app to handle uncaught exceptions by sending the stacktrace to my backend application using a (POST) webservice. In order to do this, I set up an UncaughtExceptionHandler in my parent activity:

Thread.setDefaultUncaughtExceptionHandler(new CustomExceptionHandler(this));

In my CustomExceptionHandler, I override the uncaughtException method:

@Override
public void uncaughtException(Thread thread, Throwable ex) {
    HttpURLConnection connection = null;
    try {
        URL url = new URL("http://mywebserviceurl.com?message=justatest");
        connection = (HttpURLConnection) url.openConnection();
        connection.setReadTimeout(5000);
        connection.setConnectTimeout(5000);
        connection.setRequestMethod("POST");
        connection.setDoOutput(true);
        connection.connect();
    } catch (Exception e) {
        //Handle crash
    } finally {
        if (connection != null) {
            connection.disconnect();
        }
    }
}

In order to test this I force my app to crash:

new Handler().postDelayed(new Runnable(){
    @Override
    public void run() {
        throw new RuntimeException("");
    }
}, 2500);

but my webservice is not contacted. When I put a breakpoint on the second line of the try clause, it seems like the debugger very briefly arrives at the line, then the program and debugger simply quit. I also tried creating a new thread to handle the webservice call, I tried using AsyncTasks, but the behavior remains the same: my webservice is never contacted. What is going wrong?

Thanks.