There are several ways you can convert your Excel file to a CSV format, Thanmi. 

Beforehand, could you please share the error message you encountered and the type of transactions you are trying to upload? Providing additional details will enable us to assist you more effectively. 

If you’re referring to bank transactions, you can contact your bank for assistance on how to obtain a CSV file. Alternatively, you can also either save or export your Excel file as a CSV file type.

If you meant something else, you can explore using a converter tool that allows you to easily transform your Excel file into a CSV format.
 

Keep us posted in the comments below if you need further assistance.