update custome field (has already value) using .NET SDK

[Hassan]

When I use the below statement using Atlassian .NET SDK, I am getting: Error

customfield_10114 to Newtonsoft.Json.Linq.JObject. Property with the same name already exists on object

issue.CustomFields.AddArray("Test Sets association with a Test", new string[] { "DT-2396" });

[Nic Brough -Adaptavist-]

I suspect your custom field is a select or multi-select and it already has that value selected.