WinRE does not start after the October 2025 update discovers the KB5075039 correction and what you must do

Microsoft recently launched the KB5075039 update for the Windows Recovery Environment (WinRE) on Windows 10 with the intention of correcting a failure that had been making life difficult for some users for months: WinRE did not start properly after installing an October 2025 update. WinRE is the minimum but crucial tool Windows uses to repair the system when it does not start, to diagnose hanging or to remove malware, so any failure in your boot can leave the user without that last line of defense.

The problem has its origin in the October 2025 updates. In October Microsoft publicly recognized that the KB5066835 patch had caused mice and USB keyboards to stop working within the recovery environment on Windows 11, which affected the usability of the tool for many users and that Microsoft quickly corrected. However, it was later confirmed that another update of the same band, the KB5068164 directed at Windows 10, introduced a different defect: WinRE simply did not start. Microsoft's own support page for the KB5068164 includes the note on this problem and its impact on WinRE: detail of the update KB5068164.

In view of the persistence of the failure, Microsoft yesterday published the KB5075039 update for Windows 10 which, according to the change log, explicitly corrected the situation: WinRE stopped starting after applying the October update KB5068164 and now that behavior is solved. If you want to see the update in the Microsoft Update Catalogue, the corresponding entry can be found looking for the identifier in the Microsoft Update Catalogue. They have also reported specialized means that have followed the evolution of the problem and of the correction, including BleepingComputer which has covered technical details and reactions.

Before installing KB5075039 there is an important requirement to know: the partition that houses WinRE must be at least 256 MB in size. If your WinRE occupies less of that, the installer will not be able to apply the update and it will be necessary to resize the partition. Microsoft issued instructions to make that change manually (with due care), which you can consult here: official instructions to resize the WinRE partition. Before playing partitions it is necessary to remember the obvious but essential: back up your data before resize or modify partitions, because any error with the partition tables or with the disk can leave files inaccessible.

If you are not sure whether WinRE works on your computer or how much it occupies your partition, there are simple checks you can perform with administrator privileges. The reagentc / info command returns the current state of WinRE (enabled or disabled, and the route where it is installed). To know the size of the WinRE partition you can use the Windows disk management tool (diskmgmt.msc) or the DiskPart command line utility; both will show you the size and letter or label of each volume. If you prefer a more visual route, the Windows-integrated Disk Manager also allows you to identify the WinRE partition and see its size without commands.

The KB5075039 installation can be done through Windows Update when Microsoft automatically distributes it to the affected teams, or by manually downloading the package from and applying the Microsoft Update Catalog. Please note that the equipment will need to be restarted to complete the installation, and that any intervention on partitions, startup or recovery tools requires administrator privileges and caution.

This episode leaves some clear lessons: on the one hand, even updates aimed at improving safety or reliability may have unintended effects on critical components such as WinRE; on the other, it is necessary to verify periodically that system recovery tools are operational before a real failure occurs. Official documentation on what WinRE is and how it works is very useful to understand its role and configuration, and you can read it on the Microsoft page dedicated to the theme: Windows Recovery Environment (WinRE) - Microsoft documentation.

If you have suffered the problem or just want to get ahead of possible inconvenience, check WinRE's status on your team now with reagentc / info, check the size of the dedicated partition and, if applicable, apply the KB5075039 update from Windows Update or from the Microsoft Update Catalogue. And, above all, don't forget to back up a full before redimensioning partitions or performing low-level operations on your disk.