In SharePoint 2013, when you trying to open an excel sheet with external data connection, you may see the below warning:
“This workbook contains one or more queries that refresh external data. A malicious user can design a query to access confidential information and distribute it to other users or perform other harmful actions. If you trust the source of this workbook, click Yes to enable queries to external data in this workbook. If you are not sure, click No so that changes are not applied to your workbook. Do you want to enable queries to external data in this workbook?”
Screen shot of the warning
Go to Central Administration >> Manage service applications >>
Go to your excel service application and click on it to enter the service application administration page.
Click on “Trusted File Locations”
Open your trusted location and clear the below Check box “Refresh warning enabled”
Click OK and try 🙂