Microsoft will lock millions of OneNote for Windows 10 notebooks into a view-only state on October 14, 2025. In an unusual move, the company will start degrading sync performance for the legacy app as early as June 2025, according to internal message center alerts. The end-of-support date aligns with the broader Windows 10 sunset, but the OneNote retirement is a standalone decision to consolidate its note-taking clients into a single modern app.

A Hard Deadline with a Slowdown Precursor

The timeline is deliberately aggressive:
- June 2025: Sync speeds on the OneNote for Windows 10 UWP app will be throttled. Microsoft confirmed in Message Center communications that this is intended to prod users toward the modern OneNote on Windows client.
- July 2025: In-app banners and “Switch now” prompts will begin appearing, directing users to the Microsoft Store to download the replacement app.
- October 14, 2025: The legacy app stops syncing and editing entirely. It becomes a read-only viewer—existing notes remain accessible, but no changes or new content can be added.

After that date, the app will not receive security fixes, feature updates, or any technical support.

Why Microsoft Is Killing a Working App

OneNote has existed as multiple codebases on Windows for years: the UWP app preinstalled on Windows 10, the newer Microsoft 365/Store variant, the web client, and mobile versions. That fragmentation created confusion and engineering overhead. Microsoft now wants to concentrate investment on the modern OneNote on Windows, which supports:
- Enterprise security controls like Microsoft Information Protection sensitivity labeling
- Faster feature rollouts, including upcoming Copilot AI integrations
- Unified management through Intune and other tools
- A single, clearer user experience

The legacy UWP architecture could not easily accept these modern capabilities, making consolidation inevitable.

Immediate Action for Home Users

If you see “OneNote for Windows 10” in your app title, you’re affected. Follow these steps now:

  1. Sync every notebook. Right-click each notebook name in the old app and select “Sync This Notebook.” Confirm the timestamp is recent. This pushes all content to OneDrive or SharePoint, where the new app can reach it.
  2. Verify cloud presence. Open OneNote for the web (onenote.office.com) and check that all sections and pages appear.
  3. Rescue misplaced or local-only sections. Look for “Misplaced Sections” in the legacy app. Move any local-only content into a cloud-backed notebook and sync again.
  4. Install the new OneNote on Windows from the Microsoft Store (or via WinGet). Sign in with the same Microsoft account(s). All synced notebooks should appear automatically.
  5. Validate editing. Open each notebook in the new app and make a small edit to confirm full functionality.

Do not uninstall the legacy app until you are certain everything is intact. If anything is missing, use File > Open Backups in the modern OneNote or restore from the UWP sandbox backup path.

Enterprise IT: Treat This Like a Project

For organizations, this retirement is not a casual upgrade—it’s a short, high-priority IT program. Microsoft’s official migration guide outlines a structured approach:

  • Discovery: Use Intune, SCCM, or asset management tools to inventory devices with the UWP app installed. The AppId “Office.OneNote” helps identify them.
  • Pilot: Test with a cross-section of users (heavy collaborators, teachers, frontline workers) to uncover edge cases like oversized notebooks or unsynced local content.
  • Automated backups: Leverage the onenote-uwp://backup: protocol or copy files from the per-user UWP sandbox. Collect UWPBackupStatus.json and UWPSyncStatus.json logs to verify sync health.
  • Staged rollout: Deploy OneNote on Windows via WinGet or Microsoft Store for Business. Validate that every pilot user’s notebooks appear editable.
  • Do not mass-uninstall before validation. Uninstalling the legacy app without confirmed backups can permanently destroy local-only data. Keep it installed as a read-only fallback until all critical users are verified.

Common pitfalls include large notebooks with embedded PDFs (slow sync, so trim first), multiple account mismatches (work vs. personal), and minor UX differences in the modern app. Test workflows early to reduce helpdesk volume.

The Controversial Sync Throttle

Multiple reputable outlets, including Windows Central and HowToGeek, have reported that Microsoft will intentionally degrade sync performance for the legacy OneNote starting in June 2025. The detail originates from Microsoft’s own Message Center communications to administrators. While pragmatic—it reduces support for an unsupported app and pushes users toward a more secure client—the tactic will frustrate those who rely on the legacy app’s responsiveness. Organizations should document current sync speeds before June to differentiate normal from throttled behavior, and prepare for an uptick in support tickets.

Windows 10’s Own Sunset Compounds the Pressure

October 14, 2025 also marks the end of support for Windows 10 itself. While the two events are independent, they create a double-whammy for IT planning. Microsoft offers Extended Security Updates (ESU) for Windows 10 through October 2027, but that program does not extend OneNote for Windows 10’s support. Even if you pay for OS security patches, the legacy OneNote app will still go read-only. The original source, Microsoft’s official support page, confirms that Windows 10 machines will continue to function but will not receive security updates, and it recommends upgrading to Windows 11 or enrolling in ESU.

Fallback Options if You Miss the Deadline

If you can’t complete migration before October 14, 2025:
- Use OneNote for the web as a temporary editing tool; it accesses the same cloud notebooks.
- Export critical notebooks to PDF or other archival formats from the legacy app while it’s still editable.
- Maintain the old client in read-only mode for archival retrieval while daily work moves to the new app.

Don’t Wait: Your Migration Checklist

Print or share this with your team:
- [ ] Open OneNote for Windows 10 and sync every notebook. Confirm “Synced” status.
- [ ] Look for Misplaced Sections and move them to a cloud notebook.
- [ ] Install OneNote on Windows from the Store and sign in. Verify notebooks are editable.
- [ ] If notebooks are missing, use File > Open Backups or restore from UWP backup exports.
- [ ] For enterprises: collect backup and sync status JSON logs before uninstalling the legacy app.
- [ ] Complete rollout before October 14, 2025, and keep the old app as a viewer until thoroughly validated.

Microsoft’s consolidation is a long-term win for security and feature velocity, but the immediate burden falls on users and IT teams to execute a careful migration. Start syncing and piloting immediately—June’s sync slow-down will arrive faster than you think.