Event Sender throws an OnTimer.Error regarding Value Cannot Be Null

Question / Problem: 

Intermittently, batches that are processed with KAFC Workflow agent are throwing an error and will not show in the Insight\View dashboard. 

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OnTimer.Error - System.NullReferenceException: Object reference not set to an instance of an object.

OnTimer.Error - System.ArgumentNullException: Value cannot be null.
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What could be causing the issue and, is there any method to resolve?

Answer / Solution: 

The issue can be caused by a limitation of the available memory (RAM) for the listener. A full set of the errors within the KAFC_Listener.log has been included for reference, as follows: 

2017-11-17 15:44:07,525 [24] ERROR [WebServerName:442] OnTimer.Error
System.NullReferenceException: Object reference not set to an instance of an object.
at PADService.BatchQueue.Shrink()
at PADService.BatchQueue.Cache(Batch b)
at PADService.KofaxCaptureDB.ImportBatchesCreatedAndDeletedInScan(Int32 max, Int32 unfinishedBatchTimeLimit, Int32 historyThreshold)
at PADService.Processor.AddToBatchQueueAndCheckForFinishedAndWrite(Boolean fetchKC)
at PADService.PADService.OnTimer(Object state)

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2017-11-17 15:44:17,103 [24] ERROR [WebServerName:442] OnTimer.Error
System.ArgumentNullException: Value cannot be null.
Parameter name: key
at System.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
at System.Collections.Generic.Dictionary`2.FindEntry(TKey key)
at System.Collections.Generic.Dictionary`2.TryGetValue(TKey key, TValue& value)
at PADService.KofaxCaptureDB.IsAutomatic(Session s)
at PADService.Session2.Compare(IFieldContainer fc, Boolean final, Boolean cfo)
at PADService.Session2.Compare(Boolean final)
at PADService.InsightDataDB.Buffer(Session2 s, Boolean doCleanup)
at PADService.Processor.AddToBatchQueueAndCheckForFinishedAndWrite(Boolean fetchKC)
 

Steps to Resolve: 

1. Backup the Web.Config file for each of the Event Senders (KAFC Listeners)
    
2. Edit the App Setting for the MaxBatchCacheSize from the default value (3000), to a value of 1000000 (1 million)
    - This setting limits the memory (RAM) consumed by the Listener. A value of 1000000 will effectively not limit the available memory.
    
3. Complete an IISRESET on each of the Web Servers
    
4. Test the behavior of KAFC to ensure data is processing without the same error.  

Applies to: