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Option 'module' must be set to 'NodeNext'

Option 'module' must be set to 'NodeNext' when option 'moduleResolution' is set to 'NodeNext'

This error, new to TypeScript 5.2, might be happening for a few reasons. Let's break down all the reasons why it might be happening and how to fix it.

I'm Transpiling With tsc

In this section, I'm going to assume that you're using tsc to transpile your code. I.e., you've set noEmit to false, and you're running tsc to produce JavaScript files. If you're not, you can skip to the next section.

Problem 1: Your module Config is Outdated

Choosing moduleResolution: NodeNext indicates that the code you're writing is targeting Node. Your module might be set to commonjs.

Why doesn't commonjs work?

The reason commonjs no longer works is that TypeScript files can be written with .mts file extensions. This allows you to write some files which are ES Modules, and some which are CommonJS. Using commonjs with .mts file extensions mangles the output.

Solution 1

Since TypeScript 5.2, any code written for Node must use module: "NodeNext".

Set module and moduleResolution to NodeNext in your tsconfig.json:

{
  "compilerOptions": {
    "module": "NodeNext",
    "moduleResolution": "NodeNext"
  }
}

What about Node16?

Node16 is also a valid option for module and moduleResolution:

{
  "compilerOptions": {
    "module": "Node16",
    "moduleResolution": "Node16"
  }
}

Currently, this is equivalent to if both were set to NodeNext. However, using NodeNext is safer because it's future-proof - the module resolution algorithm might change in the future, and NodeNext will always use the latest version.

Problem 2: module is Set to ESNext

All LTS Node versions now support ES Modules. If your module config option is set to ESNext, you might be trying to use ES Modules in Node.

Why doesn't ESNext work?

ESNext doesn't work for the opposite reason commonjs doesn't work - it doesn't respect the difference between .mts and .cts files.

NodeNext respects the difference between .mts and .cts files and emits the correct code for each.

Solution 2

If you want to emit ES Modules for Node, there's a better way.

  1. Set module to NodeNext
{
  "compilerOptions": {
    "module": "NodeNext",
    "moduleResolution": "NodeNext"
  }
}
  1. Add "type": "module" to your package.json
{
  "type": "module"
}

Now, your emitted code will be ES Modules, and your package.json will be set up correctly.

I'm Not Transpiling With tsc

If you're using a bundler like esbuild, swc, vite, or your framework of choice handles it, this is the section for you.

If you're not sure, check if your tsconfig.json has noEmit: true in it. If it does, you're not bundling with TypeScript.

You're Using The Wrong moduleResolution

If you're not bundling with TypeScript, you should be using moduleResolution: "bundler" and module: "ESNext":

{
  "compilerOptions": {
    "module": "ESNext",
    "moduleResolution": "bundler"
  }
}

moduleResolution: "bundler" is designed for situations where TypeScript is not responsible for emitting code. It tells TypeScript to assume that the bundler will handle emitting modules.

module: "ESNext" is required with moduleResolution: "bundler" because it most closely matches the assumptions most bundlers make about your TypeScript code.

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