C # download. xlsx File Error Resolution method

Download. xlsx file Error Resolution errors prompt: Excel finds unreadable content in "12.xlsx". Do you want to restore the contents of the workbook? If you trust the source of this workbook, click Yes. After you click Yes: Excel has completed file-level validation and repair. Some parts of this workbook may have been repaired or discarded. FileStream filestream=new FileStream (pfilename,filemode.open) long fileSize = Filestream.length; Context.response.contenttype= "Application/octet-stream"; Context.Response.AddHeader ("Content-disposition", "attachment; filename=" "+ filename +" ";"); Context.Response.AddHeader ("Content-length", filesize.tostring ()); Byte[] Filebuffer=new byte[filesize]; FileStream.Read (Filebuffer, 0, (int) fileSize); Context.Response.BinaryWrite (Filebuffer); Context.Response.End (); After adding the following line of code, the problem is solved Context.Response.AddHeader ("Content-length", filesize.tostring ());