Each month, the team at Readiness analyzes the latest Patch Tuesday updates from Microsoft and provides detailed, actionable testing guidance. This guidance is based on assessing a large application portfolio and a comprehensive analysis of the Microsoft patches and their potential impact on Windows platforms and application deployments.
For this December 2025 release cycle from Microsoft, we have grouped the critical updates and required testing efforts into different functional areas, including:
Cloud Files & Sync Providers
Organizations using OneDrive, SharePoint sync, or third-party cloud storage providers should validate sync-root connectivity and file hydration workflows. Testing should cover sync-root connection and disconnection scenarios, including hydration/dehydration, client restarts, client upgrades, unexpected client crashes, account unlink/relink flows, and multi-user scenarios.
Windows Sandbox & Virtualization
The kernel and storage virtualization components receive updates affecting Windows Sandbox functionality. Organizations using Sandbox for application testing or isolated browsing should install and enable Windows Sandbox, configure folder mappings via configuration files, and validate that mapped folders are accessible with basic file operations (create, modify, delete) functioning correctly.
Start Menu User Tiles
The Start Menu’s User Tiles UI receives updates this month. Testing should validate UI rendering (correct display, alignment, profile images), functionality (click actions, hover states, keyboard navigation), dynamic updates (profile changes reflecting immediately), error handling (missing or corrupted profile data), and performance (no lag or crashes during user switching).
December 2025’s release is stability-focused with no high-risk components. Testing effort should center on cloud file synchronization workflows for OneDrive/SharePoint users, Windows Sandbox folder mapping for virtualization environments, and Start Menu User Tiles for organizations with multi-user workstations. This lighter release provides an opportunity to complete patching before year-end corporate change freezes.
