Two file types are required for IT admins enrolled in the private preview of Unified Update Platform (UUP) for on-premises update management. Those using Windows Server Update Services (WSUS) must add .msu and .wim MIME file types to support the private preview capabilities.
The new blog post outlines steps you can follow to add these file types manually or using PowerShell. If your organization is not yet enrolled in this private preview, consider joining it before you start getting Windows updates in a unified format through various channels.
Learn more about the preview of UUP for on-premises update management in the Windows IT Pro Blog, at Preview Unified Update Platform for on-premises update management.
For detailed information on the file type requirements for UUP, please see Adding file types for Unified Update Platform on premises.