I want to add domain Alias ​​to Plesk via API

public static HttpClient _client;

public PleskAPI(string baseUrl, string username, string password)
{ 
    _client = new HttpClient { BaseAddress = new Uri(baseUrl) };

    var byteArray = Encoding.ASCII.GetBytes($"{username}:{password}");
    
    _client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(byteArray));
    
    //ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
    ServicePointManager.ServerCertificateValidationCallback = (sender, cert, chain, sslPolicyErrors) => true;
}

public static async Task<bool> AddDomain(string domainName, string ftpLogin, string ftpPassword, string ipv4, string planName)
{
    var requestBody = new { name = domainName, hosting_type = "virtual", hosting_settings = new { ftp_login = ftpLogin, ftp_password = ftpPassword }, ipv4 = new[] { ipv4 }, plan = new { name = planName } };

    var jsonContent = new StringContent(JsonConvert.SerializeObject(requestBody), Encoding.UTF8, "application/json");

    var response = await _client.PostAsync("/api/v2/domains", jsonContent);
    var responseContent = await response.Content.ReadAsStringAsync();

    Console.WriteLine(responseContent);

    return response.IsSuccessStatusCode;
}

public static async Task<bool> AddDomainAlias(string aliasName, string domainName)
{
    var xmlRequest = $@"
            <packet version=""1.6.7.0"">
              <site-alias>
                <create>
                  <pref>
                    <web>1</web>
                    <mail>0</mail>
                    <tomcat>0</tomcat>
                    <seo-redirect>0</seo-redirect>
                  </pref>
                  <site-id>16</site-id>
                  <name>{aliasName}</name>
                </create>
              </site-alias>
            </packet>";

    var xmlContent = new StringContent(xmlRequest, Encoding.UTF8, "application/xml");

    var response = await _client.PostAsync("/enterprise/control/agent.php", xmlContent);
    var responseContent = await response.Content.ReadAsStringAsync();

    Console.WriteLine(responseContent);

    return response.IsSuccessStatusCode;
}

bool success = await PleskAPI.AddDomainAlias(domainAlias, domainParent);

In the response of AddDomainAlias I get the result 200 OK. However in responseContent the result returned is:

<errcode>1029</errcode>
<errtext>Authentication method is not specified</errtext>

I checked it also added Authorization. Meanwhile, when I use AddDomain via API and the result is successful, it also created the domain on my server.

I can’t find any other documentation about create AddDomainAlias. Looking forward to everyone’s help. Thanks.