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Microsoft is announcing the end of support and retirement for Office Online Server effective December 31, 2026. After this date, Office Online Server will no longer receive security updates, bug fixes, or technical support from Microsoft. This change is part of our ongoing commitment to modernizing productivity experiences and focusing on cloud-first solutions. To help […]

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After installing the September 2025 CU for SharePoint Server 2016, 2019, and Subscription Edition. The following error is returned when deploying the solution: Reference: Trending Issue: Solution deployment fails after installing September 2025 CU for SharePoint Server Solution: October 2025 CU for SharePoint Server 2016, 2019 and Subscription Edition includes a fix for this issue: […]

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To enhance security September 2025 CU for SharePoint restricts the Windows WSS_WPG windows security group and the IIS_IUSRS windows security group from writing into the SharePoint _LAYOUTS directory (c:\program files\common files\microsoft shared\Web Server Extensions\16\TEMPLATE\LAYOUTS). As the SharePoint Configuration wizard adds the local system account of Windows (NT Authority\system) to the WSS_WPG windows security group, future […]

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SharePoint Server 2025 CU for SharePoint Server 2016, 2019 and Subscription Edition includes security hardening for SharePoint Server 2013 workflows which enforces the most recent SharePoint Workflow Manager updates to be installed on SPWFM. As a side effect this also prevents classic workflow manager workflows from running as this version does not comply with this […]

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After installing SharePoint Workflow Manager August 2025 CU on a machine which does not have a recent patch level of SharePoint Server Subscription Edition installed error messages similar to the following can be found in the logs: Could not load file or assembly ‘System.Memory, Version=4.0.1.1, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51’ or one of its dependencies. Reference: Trending Issue: […]

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Important: If September 2025 CU for SharePoint has been installed before, remove the NT Authority\system account from WSS_WPG and IIS_IUSRS local security groups of the SharePoint machines – otherwise installing the SharePoint fixes will fail. For more details check this article: Trending Issue: SharePoint fixes fail to install after installation of September 2025 CU Below […]

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Important: If September 2025 CU for SharePoint has been installed before, remove the NT Authority\system account from WSS_WPG and IIS_IUSRS local security groups of the SharePoint machines – otherwise installing the SharePoint fixes will fail. For more details check this article: Trending Issue: SharePoint fixes fail to install after installation of September 2025 CU The […]

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Important: If September 2025 CU for SharePoint has been installed before, remove the NT Authority\system account from WSS_WPG and IIS_IUSRS local security groups of the SharePoint machines – otherwise installing the SharePoint fixes will fail. For more details check this article: Trending Issue: SharePoint fixes fail to install after installation of September 2025 CU The […]

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Important: If September 2025 CU for SharePoint has been installed before, remove the NT Authority\system account from WSS_WPG and IIS_IUSRS local security groups of the SharePoint machines – otherwise installing the SharePoint fixes will fail. For more details check this article: Trending Issue: SharePoint fixes fail to install after installation of September 2025 CU The […]

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Since multiple Trending Issues have now been documented for the September 2025 CU, and it’s becoming increasingly difficult for individuals to keep track, I’ve decided to create a single summary page. Issue Status SharePoint 2013 Workflows fail in combination with Classic Microsoft Workflow Manager after September 2025 CU Warning: Upgrade to SPWFM required before July […]