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http2 regression
About this tag
The http2 regression tag covers issues where Windows updates, particularly KB5066835 for Windows 11, break local IIS-hosted sites and developer workflows by causing ERR_CONNECTION_RESET, ERR_HTTP2_PROTOCOL_ERROR, and failures of localhost-based services. Discussions focus on mitigations and rollback guides for affected developers, sysadmins, and commercial applications. Practical workarounds are available but each carries trade-offs. This tag is relevant for those troubleshooting HTTP/2 protocol errors after applying recent Windows cumulative updates.
A wide-ranging October 2025 cumulative update for Windows 11 (KB5066835), and at least one related preview package, has broken many local IIS-hosted sites and developer workflows — causing ERR_CONNECTION_RESET, ERR_HTTP2_PROTOCOL_ERROR and outright failure of localhost-based services for...