Using MS Graph Api to create Group matching suffix requirements

Question

UPDATE / Conclusion

Seems like my problem was that we use '&' and '/' in our organization names, which looks to be the problem. Creating of groups which follows the suffix rules, with department name matching [a-Z] will work.

ORIGINAL QUESTION:

I'm trying to create groups and assigning owners/users, but I keep getting this error:

The property is missing a required prefix/suffix per your organization's Group naming requirements.

Our organization got a rule that every group name requires a suffix of type "Department".

This is my new group class:

var newGroup = new Group
{
    DisplayName = $"{displayName}-{userDepartment}",
    Description = description,
    GroupTypes = new List<string> { "Unified" },
    MailEnabled = false,
    MailNickname = mailNickName,
    SecurityEnabled = true,
    AdditionalData = new Dictionary<string, object>()
    {
        {
            "owners@odata.bind", userIds.Select(x => $"https://graph.microsoft.com/v1.0/users/{x}").ToList()
        }
    }
};

What am I missing to be compliant with the requirements?

EDIT Added image:

Answer 1

I created one group naming policy same as you in my tenant like this:

Initially, I too got same error when I ran your code in my environment as below:

Note that, group naming policies are applicable for both display name and alias (mailNickName) of Microsoft 365 groups.

In my case, I used below modified code by adding suffix to both displayName & mailNickName and got the response like this:

using Microsoft.Graph;
using Azure.Identity;
using Microsoft.Graph.Models;

namespace GroupCreationApp
{
    class Program
    {
        private static string[] scopes = new[] { "Group.ReadWrite.All" };

        static async Task Main(string[] args)
        {
            var displayName = "Library Assist";
            var userDepartment = "IT";
            var description = "Self help community for library";
            var mailNickName = $"library-{userDepartment}";
            var ownerIds = new List<string>
            {
                "userid01",
                "userid02"
            };

            var groupDisplayName = $"{displayName}-{userDepartment}";

            var graphClient = GetGraphClient();

            await CreateGroup(graphClient, groupDisplayName, description, mailNickName, ownerIds);

            Console.WriteLine("Group creation completed.");
        }

        private static GraphServiceClient GetGraphClient()
        {
            var tenantId = "tenantId";
            var clientId = "appId";

            var options = new InteractiveBrowserCredentialOptions
            {
                TenantId = tenantId,
                ClientId = clientId,
                AuthorityHost = AzureAuthorityHosts.AzurePublicCloud,
                RedirectUri = new Uri("http://localhost")
            };

            var interactiveCredential = new InteractiveBrowserCredential(options);

            var graphClient = new GraphServiceClient(interactiveCredential, scopes);

            return graphClient;
        }

        private static async Task CreateGroup(GraphServiceClient graphClient, string displayName, string description, string mailNickName, List<string> ownerIds)
        {
            try
            {
                var newGroup = new Group
                {
                    DisplayName = displayName,
                    Description = description,
                    GroupTypes = new List<string> { "Unified" },
                    MailEnabled = true,
                    MailNickname = mailNickName,
                    SecurityEnabled = false,
                    AdditionalData = new Dictionary<string, object>
                    {
                        { "owners@odata.bind", ownerIds.Select(id => $"https://graph.microsoft.com/v1.0/users/{id}").ToList() }
                    }
                };

                var result = await graphClient.Groups.PostAsync(newGroup);

                Console.WriteLine($"Group '{result.DisplayName}' created successfully with ID: {result.Id}");
            }
            catch (ServiceException ex)
            {
                Console.WriteLine($"Error creating group: {ex.Message}");
            }
        }
    }
}

Response:

To confirm that, I checked the same in Portal where new Microsoft 365 group created successfully with below properties: