C# Can'；t使用sendgrid api发送附件

我有一个字节[]，它是我的ASP.NET Core 2.1应用程序中下载的pdf文件

我正在尝试将此作为附件附加到sendgrid电子邮件

public async Task SendEmail(byte[] Attachment = null)
{
    var client = new SendGridClient(apiKey);

    var msg = new SendGridMessage();

    // I also set the To, Subject, body etc etc

    msg.AddAttachment("test.pdf",Convert.ToBase64String(Attachment) ,"application/pdf","inline");
    var response = await client.SendEmailAsync(msg);

}

我得到一个“BadReqest”状态码。如果我删除AddAttachment行，则消息被接受

---

我做错了什么？

试试这样的方法：

 using (var stream = new MemoryStream(Attachment))
    {
        msg.AddAttachment("test.pdf", stream);
        var response = await client.SendEmailAsync(msg);
    }