Dynamic WASM compilation is not available in Middlewares

Why This Error Occurred

Compiling WASM binaries dynamically is not allowed in Middlewares. Specifically, the following APIs are not supported:

WebAssembly.compile
WebAssembly.instantiate with a buffer parameter

Possible Ways to Fix It

Bundle your WASM binaries using import:

middleware.ts

import { NextResponse } from 'next/server'
import squareWasm from './square.wasm?module'
 
export default async function middleware() {
  const m = await WebAssembly.instantiate(squareWasm)
  const answer = m.exports.square(9)
  const response = NextResponse.next()
 
  response.headers.set('x-square', answer.toString())
  return response
}