Classic Microsoft Teams: The option to open files in Teams will retire [MC1058266]

We will retire the option to open a file in classic Microsoft Teams starting April 15, 2025, and ending April 30, 2025. Instead, we recommend opening the file in the appropriate app (Microsoft Word, Microsoft Excel, or Microsoft PowerPoint) in the desktop or web, where we will continue to invest our development resources. This retirement is to address certain security vulnerabilities that surfaced recently with classic Teams. NOTE: This retirement will not affect file open options for the new version of Microsoft Teams.

This message applies to classic Teams for Windows desktop, classic Teams for Mac desktop, and classic Teams for the web.

This change will happen automatically by the specified date. No admin action is required. Consider notifying your users about this change and updating relevant internal documentation.