When using BarTender with an attached Excel Spreadsheet, you get:
Error Message #6670
Failed to connect to database: unexpected error from database driver
BarTender 2016, all Excel database files
BarTender 2019, older Excel files (.xls file type instead of .xlsx)
The most common cause of this problem is that you do not have the Microsoft Access Database Engine installed or you have a mismatch between the architecture of Bartender and Excel.
You can find more information on troubleshooting those problem here: Troubleshooting Excel and BarTender
You may also get this problem if you've changed a column name in your Excel file, but BarTender is still expecting the old column name. You can correct this problem by updating the Microsoft Excel file or by reconnecting BarTender to the Excel Spreadsheet.
Here's a guide on connecting BarTender to a database: Getting Started with Database Connections