Cannot edit custom fields anymore

Hi

Project Server 2013 SP1 environment.

When we try to edit a custom field (or delete one), we get an "unknown error"  on the page.

ULS log says:

[bucketHash:373E2DB8] Exception occured in method 'CustomFields.CheckOutCustomFields' System.ArgumentException: An item with the same key has already been added.   

 at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)   

 at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)   

 at Microsoft.Office.Project.Server.Events.ServerEventManager.ConfiguredServerEvents.EventHandlerConfiguration.GetInstance(ProjectSite projectSite)   

 at Microsoft.Office.Project.Server.Events.ServerEventManager.ConfiguredServerEvents..ctor(ProjectSite projectSite)   

 at Microsoft.Office.Project.Server.Events.ServerEventManager.ConfiguredServerEvents.<>c__DisplayClass8.<GetInstance>b__7()   

 at Microsoft.Office.Project.Server.Utility.LazySet`2.GetValue(TKey key, Func`1 instanceFactory)   

 at Microsoft.Office.Project.Server.Events.ServerEventManager.ConfiguredServerEvents.GetInstance(Guid siteUid)   

 at Microsoft.Office.Project.Server.Events.ServerEventManager.<GetServerEventManager>b__0(IPlatformContext context)   

 at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)   

 at Microsoft.Office.Project.Server.BusinessLayer.Generated.CustomFieldsBase.FirePreCheckOutEvent(Guid[] uids)   

 at Microsoft.Office.Project.Server.BusinessLayer.CustomFields.CheckOutCustomFields(Guid[] array)   

 at Microsoft.Office.Project.Server.Wcf.Implementation.WcfMethodInvocation.InvokeBusinessObjectMethod(String businessObjectName, String methodName, IEnumerable`1 actions) StackTrace:

 at Microsoft.Office.Project.Server.Native.dll: (sig=6ea170d1-988e-4153-9f1d-0305c0ea0309|2|microsoft.office.project.server.native.pdb, offset=3C1E)

 at Microsoft.Office.Project.Server.Native.dll: (offset=1255D)

I suspect a relation with the Nintex Workflow for Project Server that we have installed in this instance (just today). Demand Management Workflows did not fire so I tried an Event Handler Workflow just for testing purposes. It did not fire either but shortly after that we got this issue with the custom fields.

Project Server Queue job also fail.

Anyone having an idea? (apart from rollback of the database which I fear we will have to do...)

Thanks

Christoph

Christoph Muelder | Senior Consultant, MCTS, MCSE, MCT | SOLVIN information management GmbH, Germany