Try below code.
BitmapImage image = new BitmapImage();
image.DecodeFailed += new EventHandler(image_DecodeFailed);
image.DownloadFailed += new EventHandler(image_DownloadFailed);
image.BeginInit();
image.UriSource = new Uri(strImageName, UriKind.Relative);
image.DecodePixelWidth = 300;
image.EndInit();
void image_DecodeFailed(object sender, ExceptionEventArgs e)
{
MessageBox.Show("Failed");
}
void image_DownloadFailed(object sender, ExceptionEventArgs e)
{
MessageBox.Show("Failed");
}