My project allows its users to upload / download Excel sheets. But the problem is some users may be using Excel 2007(.xlsx) and some may 2003(.xls). So, what I did is when a client uploads .xls / .xlsx it should be converted to .xls and stored in server. When a client downloads the same should be converted to appropriate format.
I've successfully able to convert .xls to .xlsx and vice versa. But at some stage I'm unable to convert if the Excel file contains too many cellstyles and if the cell is spaned to cover multiple cells.
I hope you will help me to do this task i.e conversion of .xls to .xlsx. and vice versa..