Just noticed this error in the event viewer as well.
APP AS - Customer ID: 3 - An Error has occured when updating a marking item. System.Data.SqlClient.SqlException: The INSERT statement conflicted with the FOREIGN KEY constraint "FK_tblComment_tblPrincipal". The conflict occurred in database "XXXX table "dbo.tblPrincipal", column 'PrincipalID'.
The INSERT statement conflicted with the FOREIGN KEY constraint "FK_tblIntMarkHistory_tblPrincipal". The conflict occurred in database "EVCA_COMPLIANCE_US02", table "dbo.tblPrincipal", column 'PrincipalID'.
ERROR_usp_DiscoveredItem_Upd_AddMark|17695
The statement has been terminated.
The 'usp_Comment_Add' procedure attempted to return a status of NULL, which is not allowed. A status of 0 will be returned instead.
The statement has been terminated.
at System.Data.Common.DbDataAdapter.UpdatedRowStatusErrors(RowUpdatedEventArgs rowUpdatedEvent, BatchCommandInfo[] batchCommands, Int32 commandCount)
at System.Data.Common.DbDataAdapter.UpdatedRowStatus(RowUpdatedEventArgs rowUpdatedEvent, BatchCommandInfo[] batchCommands, Int32 commandCount)
at System.Data.Common.DbDataAdapter.Update(DataRow[] dataRows, DataTableMapping tableMapping)
at System.Data.Common.DbDataAdapter.UpdateFromDataTable(DataTable dataTable, DataTableMapping tableMapping)
at System.Data.Common.DbDataAdapter.Update(DataSet dataSet, String srcTable)
at System.Data.Common.DbDataAdapter.Update(DataSet dataSet)
at KVS.Accelerator.Common.TraceDLCommand.Update(IDbDataAdapter adapter, DataSet ds, Boolean RetryDLs)
at KVS.Accelerator.Items.DiscoveryItems.UpdateDS(DiscoveryItemDS DS)
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.