Microsoft SharePoint: Update to custom scripting governance in App Catalog site [MC1186368]

Message ID: MC1186368

To strengthen security and reduce the risk of ungoverned scripting, Microsoft is expanding the custom scripting governance in the App Catalog site. This change helps ensure a more secure and manageable environment in SharePoint Online.

What will happen:

Custom scripting will be disabled (setting DenyAddAndCustomizePages to 1 or $true) for the tenant-wide App Catalog site using the APPCATALOG#0 template.

When this will happen: Default custom scripting governance on the App Catalog site will take effect starting in mid-January 2026.

Who is affected: Admins managing the SharePoint tenant-wide App Catalog site and content inside.

How this affects your organization:

• App operations remain unaffected: Uploading, updating, and deploying SharePoint and Office apps will continue to work.
• Custom script-based changes will be blocked: New changes related to custom scripting in the App Catalog Site will be disabled by default; existing custom scripting related customizations will remain unaffected.

What you can do to prepare:

• Inform App Catalog site owners and helpdesk staff in your organization of this upcoming change to reduce confusion and support calls.

• To temporarily opt out of custom scripting governance for a specific site (effective for 24 hours with tenant admin approval), use the following PowerShell command:

Set-SPOSite <SiteURL> -DenyAddAndCustomizePages $false

• To update the site property bag (by default disallowed when custom script governance is enabled), use the following PowerShell commands to enable it at tenant or site level:

Set-SPOTenant -AllowWebPropertyBagUpdateWhenDenyAddAndCustomizePagesIsEnabled $true

Set-SPOSite <SiteURL> -AllowWebPropertyBagUpdateWhenDenyAddAndCustomizePagesIsEnabled $true

Learn more: 

• Security considerations of allowing custom script | SharePoint in Microsoft 365 | SharePoint | Microsoft Learn
• Allow or prevent custom script | SharePoint in Microsoft 365 | SharePoint | Microsoft Learn
• Overview of the SharePoint Framework | SharePoint | Microsoft Learn

Compliance considerations:

No compliance considerations identified, review as appropriate for your organization.

Source: Microsoft

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