How to Fix: Nextjs 15 App router: A Node.js API is used (process.version at line: 3) which is not supported in the Edge Runtime.

Your build fails because a route, dependency, or generated bundle is being compiled for the Edge Runtime while some code inside it touches a Node.js-only API such as process.version. In Next.js 15 App Router, Edge functions run in a runtime that does not expose the full Node.js environment, so even a harmless version check can break production builds.

Understanding the Root Cause

The error message:

A Node.js API is used (process.version at line: 3) which is not supported in the Edge Runtime.

means Next.js detected code that is incompatible with the Edge Runtime. In the App Router, certain files can be executed in Edge contexts, including route handlers, middleware, and sometimes code pulled into those bundles through imports.

The key technical detail is this: Edge Runtime is not Node.js. It provides Web-standard APIs like Request, Response, and fetch, but it does not support many Node globals and modules. That includes usage patterns like:

process.version
process.cwd()
fs.readFileSync()
path.join()
crypto from Node.js modules

Even if your own route file does not directly reference process.version, one of its imported dependencies might. During the build, Next.js traces imports and sees that the Edge bundle includes Node-only code, then stops with this error.

This usually happens in one of these scenarios:

• A route exports runtime = ‘edge’ but imports a server-side library that expects Node.js.
• middleware.ts imports a package that internally reads process.version.
• A shared utility file is used by both Node and Edge code paths, but it contains Node-specific logic.
• A third-party package assumes a Node runtime and is pulled into an Edge route by accident.

In your case, the fix is not to suppress the error. The correct fix is to make the route use Node.js runtime or remove the Node-specific dependency from Edge-executed code.

Step-by-Step Solution

Use this workflow to identify the failing file and fix it safely.

1. Find which route or module is running in Edge

Search your codebase for explicit Edge declarations:

export const runtime = 'edge'

Also check these locations carefully:

• app/api/**/route.ts
• middleware.ts
• app/**/page.tsx or layout files that import server utilities

If a file uses Edge and also imports a library that depends on Node internals, that is the source of the failure.

2. Switch the affected API route to Node.js runtime

If this is an API route that needs Node-compatible libraries, explicitly opt into the Node.js runtime:

export const runtime = 'nodejs'

export async function GET() {
  return Response.json({ ok: true })
}

This is the most direct fix when the route relies on packages that use process, fs, database drivers, auth libraries, or other Node-only features.

Example for an App Router API handler:

export const runtime = 'nodejs'

import { NextResponse } from 'next/server'
import someNodeLibrary from 'some-node-library'

export async function GET() {
  const result = await someNodeLibrary.doSomething()
  return NextResponse.json(result)
}

3. Remove Edge runtime from middleware-incompatible logic

If the issue comes from middleware.ts, you cannot switch middleware to full Node.js runtime in the same way as route handlers. Middleware must stay Edge-compatible. That means you need to remove any Node-only imports from it.

Bad:

import someLibrary from 'some-node-library'

export function middleware() {
  return new Response('ok')
}

Good:

export function middleware() {
  return new Response('ok')
}

If you need heavy server logic, move it out of middleware and into a Node.js route handler or server-side function.

4. Isolate shared utilities

A very common bug is importing one shared helper in both Edge and Node contexts. Split those files so Edge-safe code stays separate from Node-specific code.

Bad shared utility:

export function getRuntimeInfo() {
  return process.version
}

Better split:

// lib/runtime-info.node.ts
export function getRuntimeInfo() {
  return process.version
}

// lib/runtime-info.edge.ts
export function getRuntimeInfo() {
  return 'edge-runtime'
}

Then import the correct helper only where it is valid.

5. Check third-party packages

If you never wrote process.version yourself, the issue is likely inside a dependency. Search for the package imported by the failing route or middleware and verify whether it supports Edge runtime.

Typical incompatible packages include:

• Node-focused authentication libraries
• Database drivers built for Node sockets
• Logging libraries that inspect Node internals
• SDKs that read environment or runtime metadata using process

If the package is not Edge-compatible, you have two options:

1. Move that logic to a Node.js runtime route
2. Replace it with an Edge-compatible alternative

6. Audit imports transitively

The imported file may look innocent, but one of its nested imports can still break the build. Reduce the route temporarily until the build passes, then re-add imports one by one.

export const runtime = 'nodejs'

export async function GET() {
  return Response.json({ status: 'test' })
}

If this works, reintroduce dependencies gradually until you find the incompatible one.

7. Rebuild and verify

npm run build

If the problem came from an App Router API route, explicitly using export const runtime = ‘nodejs’ usually resolves it. If the issue came from middleware, the fix is always to remove Node-only code from middleware imports.

Example fix pattern for Next.js 15 App Router

// app/api/example/route.ts
export const runtime = 'nodejs'

import { NextResponse } from 'next/server'

export async function GET() {
  return NextResponse.json({ message: 'Runs in Node.js runtime' })
}

If you currently have this:

export const runtime = 'edge'

change it to:

export const runtime = 'nodejs'

or remove the Edge-only dependency entirely if the file must remain Edge-compatible.

Common Edge Cases

1. The error points to generated code, not your file

This often means the problem lives inside a dependency bundle. Trace backward from the route or middleware imports and identify packages that are Node-only.

2. You are not using runtime = ‘edge’ anywhere

The issue may still come from middleware.ts, which runs on Edge by design, or from framework behavior that bundles imported code into an Edge context.

3. Environment variable access is mixed with Node checks

Using process.env.MY_VAR is often handled by Next.js, but broader usage of the process object such as process.version or process.release is not Edge-safe.

4. A package works locally but fails in CI

CI builds can be stricter because production bundling and runtime analysis are more complete than local development. Always validate with a full production build.

5. Database or auth code is imported into middleware

This is a classic architecture mistake. Middleware should remain lightweight and Edge-safe. Put database access, token verification libraries requiring Node, and server SDK logic into route handlers running under nodejs.

6. Dynamic imports do not always save you

If the module is still analyzed for an Edge bundle, you can still hit compatibility errors. The safest fix is architectural separation between Edge-safe and Node-only modules.

FAQ

Can I use process.version in Next.js 15 App Router?

Yes, but only in code that runs in the Node.js runtime. It is not supported in Edge Runtime code such as middleware or Edge route handlers.

How do I know whether a route is running in Edge or Node.js?

Check whether the file exports runtime = ‘edge’ or runtime = ‘nodejs’. Also remember that middleware.ts is Edge-based and must only use Edge-compatible APIs and dependencies.

What is the fastest fix for this build error?

If the failing file is an API route and it needs Node libraries, add export const runtime = ‘nodejs’. If the failing file is middleware, remove the Node-only import and move that logic into a server route instead.

The core rule is simple: Edge code must stay Web API only, while Node-specific libraries belong in Node.js runtime handlers. Once you separate those boundaries correctly, the build error disappears and your Next.js 15 App Router project becomes much more predictable to maintain.