在Windows上，当目录(或任何子目录)中的文件路径长度大于260个符号时，就会出现此问题。

在这种情况下，您需要删除\\\\?\C:\mydir而不是C:\mydir。 大约260个符号的限制，你可以在这里阅读。

我花了几个小时来解决这个问题和删除目录的其他异常。 这就是我的解

 public static void DeleteDirectory(string target_dir)
    {
        DeleteDirectoryFiles(target_dir);
        while (Directory.Exists(target_dir))
        {
            lock (_lock)
            {
                DeleteDirectoryDirs(target_dir);
            }
        }
    }

    private static void DeleteDirectoryDirs(string target_dir)
    {
        System.Threading.Thread.Sleep(100);

        if (Directory.Exists(target_dir))
        {

            string[] dirs = Directory.GetDirectories(target_dir);

            if (dirs.Length == 0)
                Directory.Delete(target_dir, false);
            else
                foreach (string dir in dirs)
                    DeleteDirectoryDirs(dir);
        }
    }

    private static void DeleteDirectoryFiles(string target_dir)
    {
        string[] files = Directory.GetFiles(target_dir);
        string[] dirs = Directory.GetDirectories(target_dir);

        foreach (string file in files)
        {
            File.SetAttributes(file, FileAttributes.Normal);
            File.Delete(file);
        }

        foreach (string dir in dirs)
        {
            DeleteDirectoryFiles(dir);
        }
    }

这段代码有很小的延迟，这对我的应用程序并不重要。但是要注意，如果要删除的目录中有很多子目录，那么延迟可能会成为一个问题。

在继续之前，检查一下你能控制的以下原因:

该文件夹是否设置为您的进程的当前目录?如果是，请先将其更改为其他内容。 您是否从该文件夹中打开了文件(或加载了DLL) ?(并且忘记关闭/卸载它)

否则，请检查以下不在你控制范围内的合理原因:

该文件夹中有标记为只读的文件。 您没有删除其中一些文件的权限。 文件或子文件夹在资源管理器或其他应用程序中打开。

如果是上述任何一个问题，在尝试改进删除代码之前，您应该了解为什么会发生这种情况。你的应用程序是否应该删除只读或不可访问的文件?是谁给它们做的标记，为什么?

一旦排除了上述原因，仍然存在虚假失败的可能性。如果任何人持有任何被删除的文件或文件夹的句柄，删除将失败，并且有人可能会枚举文件夹或读取其文件的原因有很多:

搜索索引器 要 备份软件

处理虚假失败的一般方法是尝试多次，在尝试之间暂停。显然，您不希望一直尝试下去，因此应该在一定次数的尝试后放弃，并抛出异常或忽略错误。是这样的:

private static void DeleteRecursivelyWithMagicDust(string destinationDir) {
    const int magicDust = 10;
    for (var gnomes = 1; gnomes <= magicDust; gnomes++) {
        try {
            Directory.Delete(destinationDir, true);
        } catch (DirectoryNotFoundException) {
            return;  // good!
        } catch (IOException) { // System.IO.IOException: The directory is not empty
            System.Diagnostics.Debug.WriteLine("Gnomes prevent deletion of {0}! Applying magic dust, attempt #{1}.", destinationDir, gnomes);

            // see http://stackoverflow.com/questions/329355/cannot-delete-directory-with-directory-deletepath-true for more magic
            Thread.Sleep(50);
            continue;
        }
        return;
    }
    // depending on your use case, consider throwing an exception here
}

在我看来，像这样的帮助器应该用于所有的删除，因为虚假的失败总是可能的。然而，你应该根据你的用例调整这些代码，而不是盲目地复制它。

我的应用程序生成的内部数据文件夹，位于%LocalAppData%下，所以我的分析如下:

The folder is controlled solely by my application, and the user has no valid reason to go and mark things as read-only or inaccessible inside that folder, so I don't try to handle that case. There's no valuable user-created stuff in there, so there's no risk of forcefully deleting something by mistake. Being an internal data folder, I don't expect it to be open in explorer, at least I don't feel the need to specifically handle the case (i.e. I'm fine handling that case via support). If all attempts fail, I choose to ignore the error. Worst case, the app fails to unpack some newer resources, crashes and prompts the user to contact support, which is acceptable to me as long as it does not happen often. Or, if the app does not crash, it will leave some old data behind, which again is acceptable to me. I choose to limit retries to 500ms (50 * 10). This is an arbitrary threshold which works in practice; I wanted the threshold to be short enough so that users wouldn't kill the app, thinking that it has stopped responding. On the other hand, half a second is plenty of time for the offender to finish processing my folder. Judging from other SO answers which sometimes find even Sleep(0) to be acceptable, very few users will ever experience more than a single retry. I retry every 50ms, which is another arbitrary number. I feel that if a file is being processed (indexed, checked) when I try to delete it, 50ms is about the right time to expect the processing to be completed in my case. Also, 50ms is small enough to not result in a noticeable slowdown; again, Sleep(0) seems to be enough in many cases, so we don't want to delay too much. The code retries on any IO exceptions. I don't normally expect any exceptions accessing %LocalAppData%, so I chose simplicity and accepted the risk of a 500ms delay in case a legitimate exception happens. I also didn't want to figure out a way to detect the exact exception that I want to retry on.

编者注:尽管这个答案包含了一些有用的信息，但关于Directory.Delete的工作原理实际上是不正确的。请阅读这个答案的评论，以及这个问题的其他答案。

我以前遇到过这个问题。

The root of the problem is that this function does not delete files that are within the directory structure. So what you'll need to do is create a function that deletes all the files within the directory structure then all the directories before removing the directory itself. I know this goes against the second parameter but it's a much safer approach. In addition, you will probably want to remove READ-ONLY access attributes from the files right before you delete them. Otherwise that will raise an exception.

只需将这些代码放入您的项目中。

public static void DeleteDirectory(string target_dir)
{
    string[] files = Directory.GetFiles(target_dir);
    string[] dirs = Directory.GetDirectories(target_dir);

    foreach (string file in files)
    {
        File.SetAttributes(file, FileAttributes.Normal);
        File.Delete(file);
    }

    foreach (string dir in dirs)
    {
        DeleteDirectory(dir);
    }

    Directory.Delete(target_dir, false);
}

另外，对我个人来说，我对允许删除的机器区域添加了一个限制，因为你希望有人在C:\ windows (%WinDir%)或C:\。

你不必创建一个额外的递归方法或删除额外文件夹内的文件。这些都是通过调用自动完成的

DirectoryInfo.Delete ();

详情在这里。

像这样的东西效果很好:

  var directoryInfo = new DirectoryInfo("My directory path");
    // Delete all files from app data directory.

    foreach (var subDirectory in directoryInfo.GetDirectories())
    {
          subDirectory.Delete(true);// true set recursive paramter, when it is true delete sub file and sub folder with files too
    }

将true作为变量传递给delete方法，将删除包含文件的子文件和子文件夹。

目录或文件处于锁定状态，不能被删除。找到锁它的罪魁祸首，看看你是否能消除它。