Unable to update FeedItems (Internal Error)

Hi,

I find myself unable to update FeedItems.

var feedItemService = (FeedItemService)user.GetService(AdWordsService.v201509.FeedItemService);

var feedOperation = new FeedItemOperation

{

    operand = new FeedItem {

                    feedId = 32977028,

                    feedItemId = 3161896032,

                    attributeValues = new[] {

                        new FeedItemAttributeValue

                        {

                            feedAttributeId = attributeMap[5],

                            stringValue = "Oliver custom title"

                        }

                    }

                },

    @operator = Operator.SET

});

feedItemService.mutate(new [] { feedOperation });

I am using the .NET client library.

Google.Api.Ads.AdWords.Lib.AdWordsApiException was unhandled

  HResult=-2146233088

  Message=AdWordsApiException: One or more AdWords API errors have occurred. 

API encountered an unexpected internal error.. (Error: InternalApiError.UNEXPECTED_INTERNAL_API_ERROR, FieldPath: , Trigger: )

  Source=Google.Ads.Common

  StackTrace:

       at Google.Api.Ads.Common.Lib.AdsSoapClient.MakeApiCall(String methodName, Object[] parameters)

       at Google.Api.Ads.Common.Lib.AdsSoapClient.Invoke(String methodName, Object[] parameters)

       at Google.Api.Ads.AdWords.v201509.FeedItemService.mutate(FeedItemOperation[] operations)

       at Etammmore.Adwords.AdwordsFeedItemRepository.UpdateImpl(IReadOnlyCollection`1 feedItems) in C:\Users\*****\Documents\Visual Studio 2015\Projects\AdwordsTest\Etammmore.Adwords\AdwordsFeedItemRepository.cs:line 112

       at Etammmore.Adwords.AdwordsFeedContext.SaveChanges() in C:\Users\*****\Documents\Visual Studio 2015\Projects\AdwordsTest\Etammmore.Adwords\AdwordsFeedContext.cs:line 42

       at AdwordsTest.Program.Main(String[] args) in C:\Users\*****\Documents\Visual Studio 2015\Projects\AdwordsTest\AdwordsTest\Program.cs:line 36

       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)

       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)

       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()

       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)

       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)

       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)

       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)

       at System.Threading.ThreadHelper.ThreadStart()

  InnerException: 

       Actor=""

       HResult=-2146233087

       Lang=""

       Message=[InternalApiError.UNEXPECTED_INTERNAL_API_ERROR @ com.google.ads.api.services.common.error.InternalApiError.<init>(InternalApiErro]

       Node=""

       Role=""

       Source=System.Web.Services

       StackTrace:

            at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)

            at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)

            at Google.Api.Ads.Common.Lib.AdsSoapClient.MakeApiCall(String methodName, Object[] parameters)

       InnerException: 

Everything else like add and remove work fine, it is only the `SET`-operation that do not work. I am sure the FeedId and the FeedItemId is created and I am using a test account.

What can be the problem?

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