Microsoft has shipped a Windows WUSA installer fix that resolves over a year’s worth of pain for enterprise administrators, bundling the repair into the June 2026 Patch Tuesday cumulative updates. The bug, first acknowledged in August 2025, caused Windows updates to fail with an ERROR_BAD_PATHNAME error whenever the Windows Update Standalone Installer (WUSA) was used to deploy .msu files from a network share containing multiple such files.
WUSA is a built-in Windows command-line tool that allows administrators to install and uninstall Microsoft Standalone Update (.msu) files via the Windows Update Agent API, the sort of workhorse utility that rarely makes headlines until it quietly breaks. The failure mode was specific: it did not occur with a single .msu file, and it did not occur when files were stored locally. That combination made it a particularly awkward issue to communicate to end users, who might not immediately understand why the same update succeeded on one machine and failed on another.
What the bug actually did, and who it hit
According to Microsoft’s Windows release health dashboard, the issue affected devices running Windows 11 24H2 and 25H2, as well as Windows Server 2025, on enterprise networks. Because WUSA is not a typical update method for home users, consumer devices were largely shielded from the problem in practice. The root trigger was the update released on 28 May 2025 (KB5058499); any device that installed that update or later releases was potentially exposed.
Microsoft moved to partially mitigate the issue in September 2025, deploying a Known Issue Rollback Group Policy that automatically applied to home and non-managed business devices. Managed enterprise environments, however, had to wait considerably longer for a full resolution.
The fix finally arrived as part of the June 2026 Patch Tuesday release, covered in cumulative updates KB5079391 for Windows 11 and KB5094125 for Windows Server 2025. According to NinjaOne, KB5094125 is a cumulative security update for Windows Server 2025, released on 9 June 2026, bringing that platform to OS Build 26100.32995. It is worth noting that Microsoft subsequently released KB5099536 on 14 July 2026 to address several reported problems with KB5094125 itself, which gives some sense of the iterative nature of large cumulative updates.
June 2026 Patch Tuesday: a busy Windows WUSA installer fix and much more
The WUSA repair was not the only reason to pay attention to June’s update cycle. As Techzine reports, the June 2026 Patch Tuesday addressed more than 200 other vulnerabilities across Microsoft’s product range, making it a substantial security release by any measure.
For administrators still stuck on older updates while waiting for the fix, Microsoft has outlined a workaround in its release health dashboard: save the .msu files locally on the device before running WUSA, rather than pointing the installer at a network share. Microsoft also flagged a timing oddity worth remembering: after restarting Windows following a WUSA installation, the Update History page in Settings may not immediately reflect the correct status. Waiting at least 15 minutes before checking should give the Settings app enough time to display an accurate result.
A recurring theme in Windows update reliability
This resolution follows a pattern that will be familiar to enterprise admins. Microsoft fixed a separate issue in April 2025 that prevented enterprise customers from installing that month’s security updates via Windows Server Update Services (WSUS), and addressed an August 2025 failure that caused Windows 11 updates to abort with 0x80240069 errors. Earlier in the same update cycle, Microsoft also warned customers about potential installation issues on some devices upgraded to Windows 11 24H2 or 25H2.
Administrators currently running KB5094125 and experiencing residual problems should check whether KB5099536, released 14 July 2026, is available in their patch management pipeline, as it targets several of the issues identified after KB5094125 shipped.
