Why are my essential business apps suddenly failing, and how do I permanently solve this awful Windows 11 bug?
A recent Windows update from October 2025, identified as KB5066835, caused significant issues for some users. If you noticed that certain applications suddenly stopped working correctly, this update was the likely cause. The problem affected programs that rely on internal communication within your computer.
The update disrupted a key function that allows software to talk to your computer’s own web services. This function involves two components: localhost and the Internet Information Server (IIS). You can think of localhost as your computer’s private phone number for its own applications. IIS acts like the operator that directs these internal calls. The faulty update essentially blocked the operator, preventing applications from connecting. This caused many programs, including CRM systems and other business software, to fail and display a “Connection reset” error.
This issue specifically impacted systems running more recent versions of Windows.
- Windows 11 24H2
- Windows 11 25H2
- Windows Server 2025
Microsoft has corrected this problem. The solution is straightforward and does not require a complicated technical workaround. The fix is contained in the preview update KB5067036, released on October 28, 2025. All subsequent Windows updates will also include this correction.
To fix your system, you only need to install the latest updates for Windows. Go to your Windows Update settings and ensure your computer is fully up to date. This simple action will repair the internal communication pathway and allow your applications to function normally again. For administrators managing multiple devices, the previous temporary solution, known as a Known Issue Rollback (KIR), is no longer necessary after installing the corrective update.