When you use NiceLabel to connect to Excel .XLS type of data files, NiceLabel uses the database driver "Microsoft Jet 4.0 OLE DB Provider" by default. You might not be able to connect to such data sources with NiceLabel.
Connection to .XLSX type of Excel file is unaffected.
You would see the system error message
"Unexpected error from external database driver (1)."
"Database Login" dialog box, prompting you for the user name and password.
Install the latest Windows updates.
Install the latest NiceLabel software V2017.X or V2019.X
NiceLabel uses ACE provider to connect to .XLS Excel data sources, even if you have initially configured JET provider on the labels. The switch happens automatically when you open a label. The ACE provider is backward compatible with the JET provider, so there are no issues making the switch.
NiceLabel uses the ACE provider also for each new .XLS Excel file that you use in your solutions. If ACE provider is not available, NiceLabel downgrades to the JET provider.
The ACE provider is installed with Microsoft Office products, but can also be installed separately (you can download it from Microsoft). You can install 32-bit or 64-bit ACE provider.
You can also change the provider from "Microsoft Jet 4.0 OLE DB Provider" (JET) to "Microsoft Office XX.0 Access Database engine OLE DB Provider" (ACE) (XX is a version number of your database provider). Change the provider for each NiceLabel solution.