facebook/react · critical · Error

The React Server Writer cannot be used outside a react-serve

Error message

The React Server Writer cannot be used outside a react-server environment. You must configure Node.js using the `--conditions react-server` flag.

What it means

react-server-dom-turbopack/static (the Edge/static writer build) only resolves to a real implementation under the react-server export condition. Without that condition, this npm stub throws on import so the server-only Flight writer never executes in an unintended environment.

Source

Thrown at packages/react-server-dom-turbopack/npm/static.js:3

'use strict';

throw new Error(
  'The React Server Writer cannot be used outside a react-server environment. ' +
    'You must configure Node.js using the `--conditions react-server` flag.'
);

View on GitHub (pinned to eafeac097b)

Solutions

Start the process with node --conditions react-server
Import the static writer only from modules conditionally loaded in the react-server branch
Mirror the react-server condition in bundler/test configuration

Example fix

# before
$ node server.js   # import of react-server-dom-turbopack/static throws

# after
$ node --conditions react-server server.js

Defensive patterns

Strategy: validation

Validate before calling

const args = process.execArgv.join(' ');
if (!args.includes('react-server')) {
  throw new Error('Static writer requires --conditions react-server');
}
const RSCStatic = require('react-server-dom-turbopack/static');

Prevention

Start Edge-runtime processes in tests with the react-server condition too
Load static writer entries only inside condition-gated branches
Keep the flag in every script that can import server code

When it happens

Trigger: Importing react-server-dom-turbopack/static in a Node process without --conditions react-server, or resolving the conditionless fallback export from a client/bundler graph.

Common situations: Edge-runtime code executed under plain Node in tests; deploy scripts missing the condition flag; monorepos where the condition is set for the app but not for tooling.

Related errors

AI-assisted analysis of facebook/react@eafeac097b (2026-08-21). Data as JSON: /api/errors/a7e7881e5bb03f93. Report an issue: GitHub.