MC1184996 – (Updated) Legacy SharePoint Online Content Delivery Network (CDN) domain to be retired—review configurations

Product:

SharePoint

Platform:

Developer, Online, US Instances, Web, World tenant

Status:

Launched

Change type:

Admin impact, Retirement, Updated message, User impact

Links:

MC1066155

Details:

Summary:
The legacy SharePoint Online CDN domain publiccdn.sharepointonline.com will be retired by late April 2026. Update all hardcoded references to the new domain public-cdn.sharepointonline.com to avoid 404 errors. Validate changes before March 31, 2026, to ensure uninterrupted access to SharePoint resources.

Details:
Updated January 8, 2026: We have updated this post as a reminder. Thank you for your patience.
[Introduction]
As part of ongoing service modernization, Microsoft has migrated the hosting of SharePoint Online static assets to the Microsoft Azure Front Door (AFD) content delivery network (CDN), using the new domain public-cdn.sharepointonline.com. This migration was previously announced in MC1066155 and completed in July 2025.
This message is a follow-up notice to retire the legacy CDN domain publiccdn.sharepointonline.com. After this rollout completes, content referenced via the legacy domain will no longer be accessible, and users will receive 404 errors when trying to access resources hosted on the legacy domain.
[When this will happen:]
General Availability (Worldwide): Rollout begins March 31, 2026, and completes by late April 2026.

Change Category:
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Scope:
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Release Phase:
General Availability

Created:
2025-11-12

updated:
2026-01-09

Task Type

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Docu to Check

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MS How does it affect me

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MS Preperations

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MS Urgency

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linked item details

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summary for non-techies**

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Direct effects for Operations**

Access Issues due to Domain Retirement
Users will encounter 404 errors when trying to access resources linked to the legacy CDN domain publiccdn.sharepointonline.com, leading to disrupted access to SharePoint content.
   - roles: End Users, Developers
   - references: https://learn.microsoft.com/sharepoint/dev/spfx/extensions/get-started/hosting-extension-from-office365-cdn#update-your-solution-project-for-the-cdn-urls, https://learn.microsoft.com/sharepoint/dev/spfx/sharepoint-framework-overview

Increased Support Tickets
The retirement of the legacy CDN domain may lead to an increase in support tickets from users experiencing access issues, impacting IT support teams' workload.
   - roles: IT Support, System Administrators
   - references: https://learn.microsoft.com/sharepoint/dev/spfx/extensions/get-started/hosting-extension-from-office365-cdn#update-your-solution-project-for-the-cdn-urls, https://learn.microsoft.com/sharepoint/dev/spfx/sharepoint-framework-overview

Service Disruption
If hardcoded references are not updated, applications relying on the legacy CDN will fail, causing service disruptions for users dependent on those applications.
   - roles: Developers, End Users
   - references: https://learn.microsoft.com/sharepoint/dev/spfx/extensions/get-started/hosting-extension-from-office365-cdn#update-your-solution-project-for-the-cdn-urls, https://learn.microsoft.com/sharepoint/dev/spfx/sharepoint-framework-overview

Compliance and Security Risks
Failure to update domain allow lists may expose the organization to compliance and security risks, as access to resources may be inadvertently blocked.
   - roles: System Administrators, Compliance Officers
   - references: https://learn.microsoft.com/sharepoint/dev/spfx/extensions/get-started/hosting-extension-from-office365-cdn#update-your-solution-project-for-the-cdn-urls, https://learn.microsoft.com/sharepoint/dev/spfx/sharepoint-framework-overview

User Experience Degradation
Users may experience frustration and decreased productivity due to inability to access necessary resources, leading to a negative impact on overall user experience.
   - roles: End Users, Project Managers
   - references: https://learn.microsoft.com/sharepoint/dev/spfx/extensions/get-started/hosting-extension-from-office365-cdn#update-your-solution-project-for-the-cdn-urls, https://learn.microsoft.com/sharepoint/dev/spfx/sharepoint-framework-overview

Configutation Options**

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Potentional Risks**

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IT Security**

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explanation for non-techies**

Imagine you're driving on a highway, and suddenly, you find out that one of the exits you regularly use is going to be closed permanently. You'd need to find a new route to reach your destination, right? This is similar to what's happening with SharePoint Online's Content Delivery Network (CDN) domain. The old "exit" or domain, publiccdn.sharepointonline.com, is being closed down, and everyone needs to start using a new "exit" or domain, public-cdn.sharepointonline.com, by April 2026.

For organizations using SharePoint Online, this means checking all the "maps" or configurations, scripts, and applications that point to the old domain and updating them to use the new one. If this isn't done, when the old domain is retired, users will hit a "roadblock" or a 404 error, meaning they won't be able to access the resources they need.

Think of it like updating your address book when a friend moves to a new house. If you keep sending mail to the old address, it won't reach them. Similarly, updating to the new domain ensures that all requests for SharePoint resources reach the correct "house" or server.

It's important to make these updates before March 31, 2026, to ensure everything runs smoothly. By validating these changes early, you can avoid any service disruptions and ensure that your "mail" or data requests continue to reach their intended destination without any hiccups.

This change doesn't mean any data is lost; it's just about making sure you're using the right path to access it. So, just like you would plan a new route when a road closes, it's time to update your SharePoint configurations to keep everything on track.