Important Update for SharePoint Online Classic Publishing Sites

Microsoft has announced a major update that will impact all organizations still using classic publishing sites in SharePoint Online. As part of their ongoing push towards a more modern, secure, and scalable platform, several key changes will be rolled out starting September 15, 2025.

What’s Changing?

Custom scripting will be disabled by default – The DenyAddAndCustomizePages property will be set to true, meaning custom scripts will no longer run unless explicitly enabled.
New classic publishing sites can no longer be created – This includes site collections based on classic publishing templates and the activation of publishing features on modern sites.
New property bag management setting – A simplified method for managing property bag values without enabling custom scripting will be introduced.
Temporary PowerShell solutions available – Microsoft will provide PowerShell-based workarounds until March 15, 2026, offering a limited-time buffer for administrators.

Note: Existing classic publishing sites will continue to function, but these changes signal Microsoft’s clear focus on the Modern SharePoint experience.

Next Steps for Organizations

If your organization still relies heavily on classic publishing, now is the time to start planning your transition. This may include:

Auditing existing classic publishing sites and features
Identifying critical customizations or workflows that need to be migrated
Training users on the Modern SharePoint experience
Collaborating with IT or Microsoft partners to develop a phased migration plan

The move to Modern SharePoint brings numerous advantages — improved performance, better integration with Microsoft 365 tools, mobile responsiveness, and a cleaner, user-friendly design.

Final Thoughts

While these changes may require some adjustment, they’re ultimately a step forward in making SharePoint Online more efficient, manageable, and future-ready. By acting early, your team can ensure a smooth transition without service disruption or loss of functionality.