http2 loopback

About this tag
The http2 loopback tag covers a specific Windows 11 regression introduced by the October 2025 cumulative update KB5066835. This update broke local HTTP/2 connections, commonly referred to as localhost or loopback connections, which are essential for developers and many applications. Microsoft acknowledged the issue and began rolling out an emergency fix. The tag is relevant for users experiencing problems with local development environments or any software relying on HTTP/2 over loopback after installing this update. Discussions focus on the technical impact, workarounds, and official patch status.

  1. Windows 11 October 2025 KB5066835 Regressions: Localhost HTTP/2 and WinRE USB Input

    Microsoft has acknowledged a serious regression in its October 14, 2025 cumulative update for Windows 11 (KB5066835) and is rolling an emergency fix after the patch broke two very different but critical areas of the platform: local HTTP/2 (localhost) connections used by developers and many...
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    • http sys localhost http sys outage http.sys http2 loopback it resilience kb5066835 kb5070773 localhost http2 localhost networking microsoft patch out-of-band update patch patch management patch rollback safe os windows 11 windows update winre recovery winre usb
    • Replies: 5
    • Forum: Windows News