WebClient throw 'WebClient 请求期间发生异常'

Question

我知道这个问题在网上问了很多，但我没有找到满意的答案。

private string LocalSqlDriverDownloader()
{
    ProgBar prograssBar = new();
    string sqlLocalDBUrl = "https://download.microsoft.com/download/7/c/1/7c14e92e-bdcb-4f89-b7cf-93543e7112d1/SqlLocalDB.msi";
    string fileName = "SqlLocalDB.msi";
    string directory = $@"{Path.GetPathRoot(Environment.SystemDirectory)}Download"; // C:\Download
    if (!Directory.Exists(directory))
    {
        Directory.CreateDirectory(directory);
    }
    using WebClient webClient = new();
    webClient.DownloadProgressChanged += (s, e) =>
    {
        Application.Current.Dispatcher?.Invoke(() =>
        {
            (prograssBar.DataContext as PrograssbarWindowViewModel).PrograssBarValue = e.ProgressPercentage;
        });
    };
    webClient.DownloadFileCompleted += (s, e) =>
    {
        prograssBar.Close();
    };
    string downloadPath = $@"{directory}\{fileName}";
    try
    {
        webClient.DownloadFile(sqlLocalDBUrl, downloadPath);
    }
    catch (Exception e)
    {
        throw new Exception(e.Message);
    }
    prograssBar.ShowDialog();
    return directory;
}

我不知道为什么这会向我抛出异常，我尝试下载其他文件，http 和 https，它与结果没有任何不同。

给定的异常：

System.Exception
  HResult=0x80131500
  Message=An exception occurred during WebClient request.
  Source=PulserTesterMultipleHeads
  StackTrace:
   at PulserTesterMultipleHeads.Models.MainTestPageMV.LocalSqlDriverDownloader() in C:\Project\Models\MainTestPageMV.cs:line 955
   at PulserTesterMultipleHeads.Models.MainTestPageMV.LocalSQLDriverInstaller() in C:\Project\Models\MainTestPageMV.cs:line 905
   at PulserTesterMultipleHeads.Models.MainTestPageMV..ctor(Action closeAction, String catalogDesc) in C:\Project\Models\MainTestPageMV.cs:line 70
   at PulserTesterMultipleHeads.UserControls.MainTestPage..ctor() in C:\Project\UserControls\MainTestPage.xaml.cs:line 31

Answer 1

移除整个结构：

try
{
    webClient.DownloadFile(sqlLocalDBUrl, downloadPath);
}
catch (Exception e)
{
    throw new Exception(e.Message);
}

替换为

webClient.DownloadFile(sqlLocalDBUrl, downloadPath);

那么你仍然会得到一个错误，但至少你将能够看到哪里出了问题。异常和内部异常会毫不含糊地告诉你哪里出了问题。堆栈跟踪会告诉你哪里出错了。

事实上，你已经添加了这个块，它所做的只是删除你需要找出问题所在的信息。我们无法告诉您具体出了什么问题，因为您的代码故意将其删除。