Exception: System.NullReferenceException: Object reference not set to an instance of an object.

in one of our NON-PROD environments (luckily :-)), we encounter issue when updating a TASK record, always get below error the first time the record is updated.  The second time the same record is updated, it doesn’t get this exception error.

We noticed it from mobile side.  The first update is not transferred to mobile.  After the 2nd update, then the modification is visible in mobile.

Server log of fist update will show this exception.  The server log 2nd update doesn’t contain this exception.

Message: The following error was encounter when attempting to export a task record with the key task_id=[task_id].

Exception:

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

   at Metrix.BusinessServer.BusinessPolicies.BusObjectPolicy.AddExportColumnData(MetrixDataRow rowIn, BusObject tableMetadataIn, XmlDocument& outboundMessageInOut, XmlElement& primaryNodeInOut, XmlElement& originalNodeInOut, BusObjExport exportRowIn, List`1& columnsAddedToMessageInOut, DataRowState dataRowStateIn)

   at Metrix.BusinessServer.BusinessPolicies.BusObjectPolicy.ExportData(MetrixDataRow rowIn, BusObjExport ExportRowIn, MetrixDataRow ParentRowIn, BusObject ParentMetaDataIn)

Any idea how to further tracing the issue?

~Juni