void CertificateValidator_CertificateValidation(CertificateValidator validator, CertificateValidationEventArgs e) { ManualResetEvent ev = new ManualResetEvent(false); Dispatcher.RunAsync( CoreDispatcherPriority.Normal, async () => { await GuiUtils.HandleCertificateValidationError(this, validator, e); ev.Set(); } ).AsTask().Wait(); ev.WaitOne(); }