咱们检测到您的浏览器不兼容传输层安全协议 (TLS) 1.1 或更高版本，此协议在 Internet 上用于确保您通讯的安全性。

早上使用.Net WebClient类采集亚马逊数据，返回http 400 Bad Request错误，内容里面有“咱们检测到您的浏览器不兼容传输层安全协议 (TLS) 1.1 或更高版本，此协议在 Internet 上用于确保您通讯的安全性。”

因此就想着多是WebClient使用TLS版本太低，查了下资料，全局加上这段代码。

ServicePointManager.ServerCertificateValidationCallback += ValidateRemoteCertificate; ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

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/// <summary>
        /// Certificate validation callback. /// </summary>
        private static bool ValidateRemoteCertificate(object sender, X509Certificate cert, X509Chain chain, SslPolicyErrors error) { // If the certificate is a valid, signed certificate, return true.
            if (error == System.Net.Security.SslPolicyErrors.None) { return true; } Console.WriteLine("X509Certificate [{0}] Policy Error: '{1}'", cert.Subject, error.ToString()); return false; }

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参考连接：https://stackoverflow.com/questions/20064505/requesting-html-over-https-with-c-sharp-webclient