用户代码未处理DirectoryNotFoundException

我对try-catch和异常处理非常熟悉。我希望我的程序在找不到目录或文件时捕获异常。 每当我运行程序时,我都会收到错误“DirectoryNotFoundException未被用户代码处理-something.dll中发生了类型为“System.IO.DirectyNotFoundException”的异常,但未在用户代码中处理”

我可以看到Visual Studio在DirectoryNotFoundDirection上中断了,有什么想法吗?

try {
    LiveDownloadOperation operation = await connectClient.CreateBackgroundDownloadAsync(filePath);
    var result = await operation.StartAsync();
}
catch (FileNotFoundException filEx) {
   Debug.WriteLine(filEx.Message);
   throw filEx;
}
catch (DirectoryNotFoundException dirEx) {
   Debug.WriteLine(dirEx.Message);
   throw;
}
catch (IOException ioEx) {
    Debug.WriteLine(ioEx.Message);
    throw ioEx;
}
catch (Exception ex) {
    Debug.WriteLine(ex.Message);
    throw;
}

EDIT:在try中显示代码