Setting up NextAuth with Prisma and Neon for Edge runtime (Cannot read properties of undefined (reading 'exec'))

[LarsHanegraaf]

Hi all

I'm trying to setup NextAuth with the database strategy while running on Vercel. However I get the error Cannot read properties of undefined (reading 'exec'). I think it has to do with the Prisma client generation for edge, but I'm not sure how to move forward. Please help :)

My assumptions

• It should work without workarounds, as the docs describe that Prisma 5.12.0 has edge compatibility.
• It should work in edge environment as Neon is a supported driver for edge runtimes.
• I followed the installation guide for Prisma.
• What wasn't described in the guide, I copied from this repo (referenced in the guide)

Context

Packages

• Next.js 15.2.0
• Prisma 6.4.1
• Prisma Neon Adapter 6.4.1
• Neon Serverless 0.10.4
• Auth Prisma adapter 2.8.0

Running on a Mac M2 with Sequoia

auth.ts

import { PrismaAdapter } from "@auth/prisma-adapter";
import { Pool } from "@neondatabase/serverless";
import { PrismaNeon } from "@prisma/adapter-neon";
import { PrismaClient } from "@prisma/client";
import NextAuth from "next-auth";
import type { Session } from "next-auth";
import type { Account } from "next-auth";
import type { JWT } from "next-auth/jwt";
import MicrosoftEntraID from "next-auth/providers/microsoft-entra-id";

const neon = new Pool({
  connectionString: process.env.AUTH_POSTGRES_PRISMA_URL,
});
const adapter = new PrismaNeon(neon);
const prisma = new PrismaClient({ adapter });

declare module "next-auth" {
  interface Session {
    accessToken?: string;
  }
}

declare module "next-auth/jwt" {
  interface JWT {
    accessToken?: string;
  }
}

export const { handlers, signIn, signOut, auth } = NextAuth({
  adapter: PrismaAdapter(prisma),
  providers: [
    MicrosoftEntraID({
      authorization: {
        params: {
          scope: "openid profile email User.Read",
        },
      },
    }),
  ],
  callbacks: {
    async jwt({ token, account }: { token: JWT; account: Account | null }) {
      if (account) {
        token.accessToken = account.access_token as string;
      }
      return token;
    },
    async session({ session, token }: { session: Session; token: JWT }) {
      session.accessToken = token.accessToken;
      return session;
    },
  },
});

middleware.ts

export { auth as middleware } from "auth";

// Read more: https://nextjs.org/docs/app/building-your-application/routing/middleware#matcher
export const config = {
  matcher: ["/((?!api|_next/static|_next/image|favicon.ico).*)"],
};

export const runtime = "experimental-edge";

What doesn't work

When I start my application, I get the following error:

 ⨯ Error [TypeError]: Cannot read properties of undefined (reading 'exec')
    at (middleware)/./node_modules/.pnpm/@prisma+client@6.4.1_prisma@6.4.1_typescript@5.8.2__typescript@5.8.2/node_modules/@prisma/client/runtime/library.js (.next/server/middleware.js:575:1)
    at __webpack_require__ (.next/server/edge-runtime-webpack.js:37:33)
    at fn (.next/server/edge-runtime-webpack.js:315:21)
    at (middleware)/./node_modules/.pnpm/@auth+prisma-adapter@2.8.0_@prisma+client@6.4.1_prisma@6.4.1_typescript@5.8.2__typescript@5.8.2_/node_modules/@auth/prisma-adapter/index.js (.next/server/middleware.js:458:1)
    at __webpack_require__ (.next/server/edge-runtime-webpack.js:37:33)
    at fn (.next/server/edge-runtime-webpack.js:315:21)
    at eval (webpack-internal:///(middleware)/./auth.ts:8:78)
    at (middleware)/./auth.ts (.next/server/middleware.js:18:1)

When I clone this repo, upgrade the packages and change it to use Microsoft Entra, it seems to 'kind of' work, although still a lot of warnings are thrown.

Thanks!