WUSA bug in Windows 11: Microsoft delivers an update after a year

A bug in Windows 11 and Windows Server 2025 caused frustration among administrators for over a year. Updates via network shares failed. With the patch day in June 2026, Microsoft is now delivering a permanent solution.

Solution for update errors

Microsoft has finally fixed a long-standing problem in Windows 11 and Windows Server 2025. Installing updates via the Windows Update Standalone Installer (WUSA for short) from a network share has been failing for more than a year. Corporate networks in which IT departments use this method to distribute updates were particularly affected. WUSA is a built-in command line tool for installing standalone update files (MSU). If several of these files were in a shared folder, the process aborted. The system reported the error code “ERRORBADPATHNAME”.

Origin and interim solution

How Günter Born reported, the problem goes back to updates from May 2025. It hardly played a role for home users, as WUSA is primarily used in professional IT environments. For some target groups, Microsoft provided a temporary solution via group policy in September 2025:

Additionally, as of September 2025, this issue has been addressed using Known Issue Rollback (KIR) and is automatically resolved for most home users and unmanaged corporate devices. Restarting your Windows device can help the solution take effect on your device faster. Windows Release Health Dashboard

In larger networks, administrators had to copy the MSU files to the respective computers to run the installation. This caused considerable additional effort. In addition, it often took at least 15 minutes after a restart until the correct installation status was displayed. These delays made maintenance difficult and required adjustments or manual monitoring of automated scripts. This increased the susceptibility to errors in system maintenance.