I find that when this excel error pops up, that it is rarely for the same reason. Here are some of my quick fixes:
* Clearing the errors in the Excel Names Manager
* Creating the sheet first within Excel and using the overwrite options in your output configuration
* Saving as XLSM has worked for many
* Also, double check that your sheetnames are under 30 characters and do not contain any invalid characters e.g. ("[", ":", etc).