If you're planning to install the September 2026 SharePoint Subscription Edition Cumulative Update, there is an important change you should be aware of before updating your environment.
As part of this update, the legacy SharePoint workflow engine (SharePoint 2010 workflows) will be disabled by default on all site collections. Because Nintex for SharePoint on-premises workflows are built on the SharePoint 2010 workflow engine, this change will impact Nintex workflows unless the legacy workflow engine is re-enabled.
To avoid workflow interruptions following the update, customers should review their environment and complete the required configuration steps before deploying the September 2026 CU.
If the August 2026 CU has already been installed, the required PowerShell changes can be applied proactively ahead of the September update, allowing administrators to prepare their environments in advance.
For detailed instructions, including how to identify affected site collections and the PowerShell commands required, please refer to the following knowledge base article: