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Windows 11 updates disrupt localhost HTTP/2 connections

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1 unique sources, 2 articles

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Microsoft's October Windows 11 updates (KB5066835) and September's KB5065789 preview update have caused issues with localhost (127.0.0.1) HTTP/2 connections. Users are experiencing errors such as 'ERR_CONNECTION_RESET' or 'ERR_HTTP2_PROTOCOL_ERROR' when attempting to connect to localhost. This affects various applications, including Visual Studio debugging, SSMS Entra ID authentication, and the Duo Desktop app. The issue also affects Windows Server 2025 systems and is linked to a bug in the HTTP.sys Windows-based web server for ASP.NET Core. Microsoft has provided a temporary fix via Known Issue Rollback (KIR) for non-managed business devices and most home users. IT administrators can resolve the issue on managed devices by installing and configuring a specific KIR group policy. A permanent fix will be included in a future Windows update.

Timeline

  1. 17.10.2025 16:58 1 articles · 23h ago

    Microsoft provides temporary and permanent fixes for HTTP/2 localhost issue

    Microsoft has provided a temporary fix via Known Issue Rollback (KIR) for non-managed business devices and most home users. IT administrators can resolve the issue on managed devices by installing and configuring a specific KIR group policy. A permanent fix will be included in a future Windows update.

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  2. 17.10.2025 01:25 2 articles · 1d ago

    Windows 11 updates disrupt localhost HTTP/2 connections

    The issue also affects Windows Server 2025 systems and is linked to a bug in the HTTP.sys Windows-based web server for ASP.NET Core. The problem can be triggered by various conditions, including the timing of recent device restarts and update installations, as well as the device's internet connectivity.

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Information Snippets

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