Forms-Customizer (SPFx) no longer works.

Question

Hello,

We have two clients reporting that Forms-Customizer (SPFx) is no longer working. The issue appears to be tenant-wide and is affecting all lists and sites.

Could you confirm whether Microsoft is currently rolling out any changes that might be causing this issue?

I can provide more details if needed.

Thank you.

Answer 1

Hi @Rytis Daskevicius

Having a tenant-wide issue that takes down custom forms across all lists and sites for multiple clients is certainly a critical situation. I understand that your SPFx Forms-Customizers have suddenly stopped working and you are looking to confirm if a recent Microsoft rollout is the root cause.

At this time, Microsoft has not released any official service health advisories or announcements regarding an outage or intentional change designed to break SPFx Form Customizers. However, there is a major recent rollout in SharePoint Online that is almost certainly causing this exact behavior.

As of March 1, 2026, Microsoft officially began enforcing Content Security Policy (CSP) in SharePoint Online. This is a tenant-level security change that directly impacts SPFx solutions. When CSP is enforced, SharePoint automatically blocks inline JavaScript, scripts loaded from untrusted sources, and dynamic script injection patterns. If your Form Customizer relies on any of these methods, the extension will fail to load, typically without displaying any obvious error messages on the user interface.

To prevent your solutions from breaking, you will need to take the following steps:

• Trust External Scripts: Ensure all external script locations your web parts use are added as trusted script sources. This can be configured at the tenant level without needing to update the SPFx solution code itself.
• Remove Inline Scripts: You must move all inline scripts to external .js files, which can then be defined as trusted sources. Note: This step will require updating and redeploying the SPFx solution package.

How to identify blocked scripts:

You can easily find out which script locations need to be added to the trusted list by opening the browser's Developer Tools (F12) console while trying to load the form. You will see warning messages indicating the blocked scripts. Look for console errors starting with:

"Loading the script '<path to script>' violates the following..." > or "Executing inline script violates the following Content Security Policy directive..."

If your team needs more time to review and update the affected SPFx solutions, there is an option to postpone the CSP enforcement by 90 days. A SharePoint Administrator can apply this delay by running the following cmdlet in the SharePoint Online Management Shell:

Set-SPOTenant -DelayContentSecurityPolicyEnforcement $true

Note: This option is available in the SPO Management Shell version 16.0.26712.12000 (November 2025) or higher.

I hope this information helps.

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Answer 2

There is no information indicating that Microsoft is rolling out changes that would retire or disable SharePoint Framework (SPFx) form or field customizers.

Recent official updates instead confirm continued support for SPFx customizations:

• Field customizers in lists and libraries are explicitly not being retired after internal evaluation and ecosystem feedback.
• SPFx 1.15 introduced the Form Customizer Extension as a supported feature for customizing new, edit, and display forms in lists and document libraries.
• SPFx 1.16 includes multiple fixes for SPFx extensions and form customizers (for example, issues with form customizers in history view and classic mode), which indicates ongoing investment rather than deprecation.

Given that the issue is tenant‑wide across all lists and sites for multiple clients, and there is no published retirement or breaking change in the provided documentation, the next steps are:

1. Verify whether the affected tenants recently changed SPFx version usage (e.g., upgraded to 1.15/1.16) or introduced new customizations.
2. Check the Microsoft 365 Service Health Dashboard for any SharePoint Online or SPFx incidents.
3. If nothing is listed, open a support ticket via the Microsoft 365 admin center so engineering can review backend logs for those tenants and confirm whether a regression or service issue is affecting SPFx form customizers.

For new or replacement implementations, consider whether some scenarios could be addressed with Custom formatting or other modern approaches, but this is optional and does not replace SPFx form customizers where full logic is required.

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References:

• Support update for SharePoint framework field customizers in lists and document libraries
• SharePoint Framework v1.15 release notes
• SharePoint Framework v1.16 release notes
• Modernize customizations