Error: EMFILE too many open files

Node Emfile Too Many Files that appears only in CI or only in production usually traces to a gap between the build environment and the runtime environment. Node.js applications built on one Node version and run on another frequently encounter this class of error. The standard preventive: pin Node version in both the build pipeline and the runtime image using the same identifier — for example, node:20.11.0-alpine rather than node:20-alpine. The minor version matters because V8 updates within minor releases can affect runtime behavior. For TypeScript projects, the compiled JavaScript must target the runtime Node version's supported JavaScript features — check tsconfig.json's target and lib settings. Native modules (compiled with node-gyp) must be compiled for the runtime architecture and Node version, not the build machine's — use npm rebuild in the runtime Dockerfile stage after copying node_modules. Environment variables available during npm run build (like NODE_ENV) affect bundling behavior and may produce different output than expected in production.