WebClient 在调用 UploadString() 时抛出错误

Question

我必须处理来自 API（在我的 Windows 应用程序中）的 JSON 数据，并且我正在尝试使用 WebClient.UploadString(); 发出 POST 请求；下面是我的代码，但它抛出错误，我尝试了各种选项，但无法将 JSON 复制为字符串。string result = "";        string url = "https://30prnabicq-dsn.algolia.net/1/indexes/*/queries?x-algolia-agent=Algolia for vanilla JavaScript (lite) 3.24.12;JS Helper 2.24.0;vue-instantsearch 1.5.0&x-algolia-application-id=30PRNABICQ&x-algolia-api-key=dcccebe87b846b64f545bf63f989c2b1";        string json = "{\"requests\":[{\"indexName\":\"vacatures\",\"params\":\"query=&hitsPerPage=20&page=0&highlightPreTag=__ais-highlight__&highlightPostTag=__/ais-highlight__&facets=[\"category\",\"contract\",\"experienceNeeded\",\"region\"]&tagFilters=\"}]}";        using (var client = new WebClient())        {            client.Headers[HttpRequestHeader.Host] = "30prnabicq-dsn.algolia.net";            client.Headers[HttpRequestHeader.UserAgent] = "Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0";             client.Headers[HttpRequestHeader.Accept] = "application/json";             client.Headers[HttpRequestHeader.AcceptLanguage] = "en-US,en;q=0.5";             client.Headers[HttpRequestHeader.AcceptEncoding] = "gzip, deflate, br";             client.Headers[HttpRequestHeader.Referer] = "https://bouwjobs.be/";            client.Headers[HttpRequestHeader.ContentType] = "application/json";             client.Headers[HttpRequestHeader.ContentLength] = "249";             client.Headers[HttpRequestHeader.Origin] = "https://bouwjobs.be";             client.Headers[HttpRequestHeader.Connection] = "keep-alive";            client.Headers[HttpRequestHeader.Cache - Control] = "max-age=0";            result = client.UploadString(url, "POST", json);            return result;        }请指导我更正我的代码。注意 - 我在我的代码中包含了一些受限制的标头，但即使在注释掉这些标头之后它也会抛出错误。