Microsoft confirmed that Windows 11 KB5066835 breaks localhost (127.0.0.1) HTTP/2 connections, which means locally hosted apps can no longer connect to your network, but that’s not the only problem.

Windows updates usually bring security enhancements, bug fixes and new features. Sometimes, though, these updates can also break parts of the operating system. Unfortunately, some updates for ...

Microsoft has fixed a known issue breaking HTTP/2 localhost (127.0.0.1) connections and IIS websites after installing recent Windows security updates. This bug affects both Windows 11 and Windows ...

The problem first surfaced on Microsoft's own support forums and quickly spread to Stack Overflow and Server Fault after the October 2025 cumulative update (KB5066835) landed, which appears to have ...

If you encounter the Localhost refused to connect error message when running any web server on your local Windows 11/10 computer, then this post is intended to help ...

Security researchers say Meta and Yandex used native Android apps to listen on localhost ports, allowing them to link web browsing data to user identities and bypass typical privacy protections.

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