Description: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Runtime.InteropServices.COMException (0x800A03EC): Microsoft Excel cannot access the file 'xxxxxlsx'. There are several possible reasons: ? The file name or path does not exist. ? The file is being used by another program. ? The workbook you are trying to save has the same name as a currently open workbook. at Microsoft.Office.Interop.Excel.Workbooks
After sometime when I was about to give up because the solutions I was seeing on the web either say go play with DcomConfig or hack registry keys yeah like some one is gonna let me do that on prod server.
Finally found MS document that hints the below procedure it works and best part don't need to mess with registry keys.