Symptoms
You receive "The remote server returned an error: (500) Internal Server Error." in the workflow enginge like Nintex or in ULS.
Furthermore you're receiving errors in ULS log at the time you get the Internal Server Error:
03.03.2016 11:40:36.09 w3wp.exe (SP-APP01.contoso.com:0x3584) 0x45C0 SharePoint Foundation DistributedCache agyfw Unexpected Unexpected error occurred in method 'GetObject' , usage 'Distributed Logon Token Cache' - Exception 'Microsoft.ApplicationServer.Caching.DataCacheException: ErrorCode<ERRCA0018>:SubStatus<ES0001>:The request timed out.. Additional Information : The client was trying to communicate with the server : net.tcp://SP-WFE01.contoso.com.int:22233 at Microsoft.ApplicationServer.Caching.DataCache.ThrowException(ResponseBody respBody, RequestBody reqBody) at Microsoft.ApplicationServer.Caching.DataCache.InternalGet(String key, DataCacheItemVersion& version, String region, IMonitoringListener listener) at Microsoft.ApplicationServer.Caching.DataCache.<>c__DisplayClass49.<Get>b__48() at Microsoft.SharePoint.DistributedCaching.SPDistributedCache.GetObject(String key)'. d7e3649d-9988-4058-a54c-f7494cad57a0
bzw. auch
03.03.2016 11:40:42.52 w3wp.exe (SP-APP01:0x2E24) 0x3330 SharePoint Portal Server User Profiles ajxt4 Unexpected Microsoft.Office.Server.Social.SPSocialFeedManager.GetFeed: Microsoft.Office.Server.Microfeed.MicrofeedException: ServerErrorFetchingConsolidatedFeed : ( Unexpected exception in FeedCacheService.GetConsolidatedFeed: Unable to create a DataCache. SPDistributedCache is probably down.. ) : Correlation ID:d7e3649d-6998-4058-a54c-f61ee364f1f8 : Date and Time : 3/3/2016 11:40:42 AM at Microsoft.Office.Server.Microfeed.SPMicrofeedThreadCollection.PopulateConsolidated(SPMicrofeedRetrievalOptions retOptions, SPMicrofeedContext context) at Microsoft.Office.Server.Microfeed.SPMicrofeedThreadCollection.Populate(SPMicrofeedRetrievalOptions retrievalOptions, SPMicrofeedContext context) at Microsoft.Office.Server.Microfeed.SPMicrofeedManager.CommonGetFeedFor(SPMicrofeedRetrievalOptions retrievalOptions) at Microsoft.Office.Server.Microfeed.SPMicrofeedManager.GetMyConsolidatedFeed(SPMicrofeedRetrievalOptions feedOptions) at Microsoft.Office.Server.Social.SPSocialFeedManager.Microsoft.Office.Server.Social.ISocialFeedManagerProxy.ProxyGetFeed(SPSocialFeedType type, SPSocialFeedOptions options) at Microsoft.Office.Server.Social.SPSocialFeedManager.<>c__DisplayClass4b`1.<S2SInvoke>b__4a() at Microsoft.Office.Server.Social.SPSocialUtil.InvokeWithExceptionTranslation[T](ISocialOperationManager target, String name, Func`1 func) d7e3649d-6998-4058-a54c-f61ee364f1f8
You already did Distributed Cache troubleshooting and Get-CacheClusterHealth reports healthy (score 10).
Cause
This is a known bug in AppFabric 1.1 Caching Services which is an essential part of SharePoint and responsible for issueing tokens. If this component fails, we get an access denied error as no token is issued.
Resolution
Please update at least to AppFabric Caching Service 1.1 CU3 or higher. It needs to be patched separately from SharePoint Service Pack's / CU's. App Fabric 1.1 is part of SharePoint 2013.
You can find AppFabric 1.1 CU5 here: http://support2.microsoft.com/kb/2932678
More Information