这是我们用于向苹果发送推送通知以更新Apple Wallet Pass的代码：我们正在使用.net API服务发送推送通知给苹果。

var handler = new HttpClientHandler();
handler.ClientCertificateOptions = ClientCertificateOption.Manual;
handler.ClientCertificates.Add(new X509Certificate2(X509Certificate2.CreateFromEncryptedPemFile("passcertificate.pem", "password", "passkey.pem").Export(X509ContentType.Pfx))); 

using (var httpClient = new HttpClient(handler))
{
    using (var request = new HttpRequestMessage(new HttpMethod("POST"), "https://api.push.apple.com/3/device/pushtoken"))
    {
        request.Headers.TryAddWithoutValidation("apns-topic", "pass.com.companyname.loyaltycard");
        request.Headers.TryAddWithoutValidation("apns-priority", "10"); 

        request.Content = new StringContent("{}");
        request.Content.Headers.ContentType = MediaTypeHeaderValue.Parse("application/x-www-form-urlencoded"); 

        var response = await httpClient.SendAsync(request);
    }
}

上述推送通知调用返回状态200：并且作为响应不返回错误。
但是Apple服务器没有调用我们的Web API来获取更新的序列号：
webServiceURL/version/devices/deviceLibraryIdentifier/registrations/passTypeIdentifier？passesUpdatedSince=date
请帮助我找出可能出错的地方。