Next.js: node-tfhe WASM loading fails with standalone output

[gustavovalverde]

Summary

When using @zama-fhe/relayer-sdk in a Next.js application with output: "standalone", the node-tfhe dependency fails to load its WASM file at runtime.

Environment

• @zama-fhe/relayer-sdk: 0.3.0-6
• node-tfhe: 1.4.0-alpha.3 (transitive dependency)
• Next.js: 16.0.10
• Turbopack (Next.js 16 default bundler)

Error

ENOENT: no such file or directory, open '/ROOT/node_modules/node-tfhe/tfhe_bg.wasm'

Root Cause

node-tfhe/tfhe.js uses __dirname to locate its WASM file:

const wasmPath = `${__dirname}/tfhe_bg.wasm`;
const wasmBytes = require('fs').readFileSync(wasmPath);

When Next.js bundles this with output: "standalone", __dirname is resolved at build time to a placeholder path (/ROOT/...) instead of the actual runtime path.

Workaround

Add node-tfhe to serverExternalPackages in next.config.ts:

const nextConfig: NextConfig = {
  output: "standalone",
  serverExternalPackages: [
    "node-tfhe",
  ],
};

This prevents Next.js from bundling the package, allowing __dirname to resolve correctly at runtime.

Suggestion

Consider documenting this workaround for Next.js users, or exploring alternative WASM loading strategies that work with bundlers (e.g., using import.meta.url or async WASM imports).

[gustavovalverde]

Update: The same issue affects node-tkms which also uses __dirname for WASM loading.

Complete workaround:

serverExternalPackages: [
  "node-tfhe",
  "node-tkms",
],