Windows 11 updates break localhost (127.0.0.1) HTTP/2 connections
ID: 33219c10-d392-5170-bf9d-39dc98647bbe
STIX ID: report--33219c10-d392-5170-bf9d-39dc98647bbe
Feed Name: Bleeping Computer
Microsoft's October Windows 11 updates (KB5066835 and a September preview KB5065789) disrupted HTTP/2 connections to localhost (127.0.0.1), producing errors such as ERR_CONNECTION_RESET and ERR_HTTP2_PROTOCOL_ERROR and breaking local-dependent applications (Visual Studio debugging, SSMS Entra ID authentication, Duo Desktop, IIS-hosted sites). Reported workarounds included disabling HTTP/2 via registry keys or uninstalling the updates, and Microsoft later issued a Known Issue Rollback (KIR) update and guidance via Windows Update to resolve the issue.
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