Information
This policy setting controls whether Excel prompts users to update automatic links, or whether the updates occur in the background with no prompt. The recommended state for this setting is: Enabled. If an Excel workbook contains links to other documents and users are not prompted to approve them, the contents of the workbook might change without the users' knowledge because the linked files have changed. By default, users are prompted to update automatic links.
Solution
To implement the recommended configuration state, set the following Group Policy setting to Enabled. User Configuration\Administrative Templates\Microsoft Excel 2013\Excel Options\Advanced\Ask to Update Automatic Links Impact: Enabling this setting enforces the default configuration in Excel, and therefore is unlikely to cause usability issues for most users.