NullReferenceException : Object reference not set to an instance of an object. : Caused by NullReferenceException at Sdl.Tms.Ps.MultilingualExcel. Object reference not set to an instance of an object. : at Sdl.Tms.Ps.MultilingualExcel.PreProcessorWorker.CreateMultilingualFile(FileInfo sourceFileInfo) at Sdl.Tms.Ps.MultilingualExcel.PreProcessorWorker.Execute() at Sdl.Tms.Ps.MultilingualExcel.PreProcessor.Execute() at Sdl.Tms.MessageProcessing.WorkerRequestProcessor.ExecuteMessage()
Its hard to say the root cause of this. I would look to raise this as a new support request as there are a number of factors that could bring this result such as Excel versions, content within and configuration.
If we have the specific file then we can look to find the root cause and any possible workarounds.