Upgrade Turbopack HMR websocket in nextjs proxy - #90
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Next 16 defaults `next dev` to Turbopack, which serves its HMR websocket at /_next/hmr rather than the legacy webpack /_next/webpack-hmr. The template only upgraded the webpack path, so the Turbopack connection fell through to `location /` without upgrade headers and failed. Since Next 16.3 that failure aborts client hydration, leaving dev pages non-interactive. Match both paths with one regex block so HMR works under either bundler. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Problem
Next 16 defaults
next devto Turbopack, which serves its HMR websocket at/_next/hmrinstead of the legacy webpack/_next/webpack-hmr. Thenextjsproxy template only has an upgrade block for the webpack path, so the Turbopack connection falls through tolocation /(noUpgrade/Connectionheaders) and fails the WebSocket handshake.Since Next 16.3 that failed connection is established during client bootstrap/hydration, and its failure aborts hydration — leaving dev pages non-interactive (e.g. login forms don't respond). It only affects local dev behind this proxy; production (
next start) has no HMR and is unaffected.Fix
Match both HMR paths with a single regex
location, so it works under either bundler without duplicating the proxy directives:A regex location outranks the
location /prefix, so both paths still match here.${NGINX_PROXY_PASS}has no URI part, so it's valid in a regex location.Verification
Built the
nextjsimage with this change and ran a Next 16.3 (Turbopack) app behind it. The/_next/hmrwebsocket now completes the upgrade (HTTP 101), stays open, and receives Turbopack HMR messages (isrManifest,turbopack-connected). Login / interactivity restored. The legacy/_next/webpack-hmrpath continues to upgrade fornext dev --webpack.