Bug report

What is the current behavior?

When using webpack-dev-server with hot: true and a separate styles entry point, the compiled styles.js throws at runtime:

Error: [HMR] Hot Module Replacement is disabled.

This started happening after [email protected] was published (2026-03-23).

What is the expected behavior?

module.hot should evaluate as truthy in the styles entry when HMR is enabled, so webpack/hot/dev-server.js doesn't throw.

Minimal reproduction

https://github.com/FrozenPandaz/webpack-hmr-styles-repro

git clone https://github.com/FrozenPandaz/webpack-hmr-styles-repro
cd webpack-hmr-styles-repro
pnpm install
pnpm serve
# Open http://localhost:4200 — browser console shows the error

Pinning tapable to 2.3.0 resolves the issue.

Root cause

HotModuleReplacementPlugin taps parser.hooks.evaluateIdentifier.for("module.hot") with before: "NodeStuffPlugin". This ensures module.hot evaluates as truthy so webpack keeps the if (module.hot) branch.

However, NodeStuffPlugin never taps evaluateIdentifier for module.hot, so the before reference is invalid.

• tapable 2.3.0: invalid before → tap inserted at position 0 → module.hot evaluates truthy → works
• tapable 2.3.1: tapable PR #198 deletes invalid before names → tap goes to natural position → module.hot evaluates falsy for styles entry → throws

Other relevant information:

• webpack: 5.105.4
• webpack-cli: 7.0.2
• webpack-dev-server: 5.2.3
• tapable: 2.3.1 (works with 2.3.0)
• Node.js: v24.9.0
• OS: Linux