February 2026 CU for SharePoint Server Subscription Edition: Addressing Installation Prerequisites

February 2026 CU for SharePoint Server Subscription Edition: Addressing Installation Prerequisites

The February 2026 Cumulative Update (CU) for SharePoint Server Subscription Edition is now available. This update delivers essential fixes and enhancements to maintain the security and performance of your SharePoint environment. However, a crucial prerequisite must be addressed before installation.

Important: If your farm is currently patched with the September 2025 CU, you must remove the NT Authority\system account from the WSS_WPG and IIS_IUSRS local security groups on all SharePoint servers before applying the February 2026 CU. Failure to do so will result in installation failures. For detailed information, refer to this article.

This security configuration change is necessary to resolve an issue introduced after the September 2025 CU. Neglecting this step will prevent the successful application of the latest fixes.

Pre-Installation Checklist

• Verify your current farm patch level.
• If the September 2025 CU is installed, remove the NT Authority\system account from the specified security groups.
• Back up your SharePoint farm before initiating the update process.

After the update is complete, thoroughly test your SharePoint environment to ensure proper functionality and stability.

Further Considerations

This CU also addresses several known issues and includes performance improvements. It is highly recommended to apply this update to maintain a secure and optimized SharePoint environment. Always refer to the official Microsoft documentation for the complete list of changes and known issues.