An item with the same key has already been added Hatası

Merhabalar bir müşterimi,n sisteminde sabahtran beri admin paneleine girerken bu hatayı veriyor. Yazılımcılarına uzun süredir ulaşamadığıından beraber çözüm arıyoruz soruna.

Sebebi ne olabilir acaba ?

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

[ArgumentException: An item with the same key has already been added.]
   System.ThrowHelper.ThrowArgumentException(ExceptionResource resource) +56
   System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) +10324558
   System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value) +12
   Golbet.Data.AdminUser.LoadPermissions() in E:\source\Odds\GalaxyBet\Golbet.Data\Custom\DB\AdminUser.cs:34
   Golbet.Web.Security.GolbetAdminUserProvider.RegisterAuthenticatedUser(AdminUser user) in E:\source\Odds\GalaxyBet\Golbet.WebLib\Web\Security\GolbetAdminUserProvider.cs:28
   Galaxy.Web.Areas.Admin.Controllers.UserController.Login(String username, String passwd) in E:\source\Odds\GalaxyBet\Galaxy\Galaxy.Web\Areas\Admin\Controllers\UserController.cs:41
   lambda_method(ExecutionScope , ControllerBase , Object[] ) +105
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +236
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +31
   System.Web.Mvc.<>c__DisplayClassd.<InvokeActionMethodWithFilters>b__a() +85
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) +657427
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +288
   System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +658164
   System.Web.Mvc.Controller.ExecuteCore() +125
   System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__4() +48
   System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +21
   System.Web.Mvc.Async.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) +15
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +85
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +51
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +454
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +263

Sorun kodlama hatasından kaynaklanıyor maalesef. Çevrenizde c# bilen birisi varsa ona gösterirseniz sorunu giderecektir.

Aslında uzun zamandır sorunsuz şekilde çalışıyordu her ne olduysa bufün sabah bu hatayı vermiş.

Konu hakkında bilgili yazılımcı arkadaşımız varsa detaylıca görüşmek istiyoruz.

PM gönderdim