Windows需要安装你想要使用的UI语言。如果没有，它没有办法神奇地知道翻译后的信息是什么。

在安装了pt-PT的en-US windows 7 ultimate中，以下代码:

Thread.CurrentThread.CurrentUICulture = CultureInfo.GetCultureInfo("pt-PT");
string msg1 = new DirectoryNotFoundException().Message;

Thread.CurrentThread.CurrentUICulture = CultureInfo.GetCultureInfo("en-US");
string msg2 = new FileNotFoundException().Message;

Thread.CurrentThread.CurrentUICulture = CultureInfo.GetCultureInfo("fr-FR");
string msg3 = new FileNotFoundException().Message;

生成pt-PT, en-US和en-US格式的消息。由于没有安装法语文化文件，它默认为windows默认(已安装?)语言。

基于Undercover1989答案，但考虑参数以及当消息由多个资源字符串组成时(如参数异常)。

public static string TranslateExceptionMessage(Exception exception, CultureInfo targetCulture)
{
    Assembly a = exception.GetType().Assembly;
    ResourceManager rm = new ResourceManager(a.GetName().Name, a);
    ResourceSet rsOriginal = rm.GetResourceSet(Thread.CurrentThread.CurrentUICulture, true, true);
    ResourceSet rsTranslated = rm.GetResourceSet(targetCulture, true, true);

    var result = exception.Message;

    foreach (DictionaryEntry item in rsOriginal)
    {
        if (!(item.Value is string message))
            continue;

        string translated = rsTranslated.GetString(item.Key.ToString(), false);

        if (!message.Contains("{"))
        {
            result = result.Replace(message, translated);
        }
        else
        {
            var pattern = $"{Regex.Escape(message)}";
            pattern = Regex.Replace(pattern, @"\\{([0-9]+)\}", "(?<group$1>.*)");

            var regex = new Regex(pattern);

            var replacePattern = translated;
            replacePattern = Regex.Replace(replacePattern, @"{([0-9]+)}", @"${group$1}");
            replacePattern = replacePattern.Replace("\\$", "$");

            result = regex.Replace(result, replacePattern);
        }
    }

    return result;
}

这可能是一个有争议的观点，但是与其将区域性设置为en-US，不如将其设置为Invariant。在“不变区域性”中，错误消息是英文的。

Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;
Thread.CurrentThread.CurrentUICulture = CultureInfo.InvariantCulture;

它的优点是看起来没有偏见，特别是对于非美式英语地区。(也就是避免同事的冷嘲热讽)

关于。net Core和以上，线程文档。CurrentUICulture推荐使用CultureInfo。属性检索和设置当前区域性。

CultureInfo.CurrentUICulture = CultureInfo.InvariantCulture;

在一个相关的GitHub问题上，Tarek Mahmoud Sayed建议使用CultureInfo。defaultthreadcurrentuicculture以确保稍后创建的其他线程也将获得相同的区域性:

CultureInfo.DefaultThreadCurrentUICulture = CultureInfo.InvariantCulture;

后者只在。net Framework 4.5(和。net Core 1.0)之后才可用。

必须在IIS上进行更改。进入IIS管理器>选择站点> . net全球化>在那里将UI文化设置为英文。

在另一篇SO文章中可以看到更详细的答案。

Setting Thread.CurrentThread.CurrentUICulture will be used to localize the exceptions. If you need two kinds of exceptions (one for the user, one for you) you can use the following function to translate the exception-message. It's searching in the .NET-Libraries resources for the original text to get the resource-key and then return the translated value. But there's one weakness I didn't find a good solution yet: Messages, that contains {0} in resources will not be found. If anyone has a good solution I would be grateful.

public static string TranslateExceptionMessage(Exception ex, CultureInfo targetCulture)
{
    try
    {
        Assembly assembly = ex.GetType().Assembly;
        ResourceManager resourceManager = new ResourceManager(assembly.GetName().Name, assembly);
        ResourceSet originalResources = resourceManager.GetResourceSet(Thread.CurrentThread.CurrentUICulture, createIfNotExists: true, tryParents: true);
        ResourceSet targetResources = resourceManager.GetResourceSet(targetCulture, createIfNotExists: true, tryParents: true);
        foreach (DictionaryEntry originalResource in originalResources)
            if (originalResource.Value.ToString().Equals(ex.Message.ToString(), StringComparison.Ordinal))
                return targetResources.GetString(originalResource.Key.ToString(), ignoreCase: false); // success

    }
    catch { }
    return ex.Message; // failed (error or cause it's not smart enough to find texts with '{0}'-patterns)
}