facebook/react · critical · Error

The React Server cannot be used outside a react-server envir

Error message

The React Server 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-parcel/static is the Edge/static build of the Flight server. The package's export map resolves the real implementation only under the react-server Node condition; everything else resolves to this stub, which throws at import time so the server serialization runtime never loads inside a non-react-server process.

Source

Thrown at packages/react-server-dom-parcel/static.js:10

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow
 */

throw new Error(
  'The React Server 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

1. Start Node with the condition flag: node --conditions react-server server.js
2. Load the server entry only inside code paths that run under the react-server condition (guarded dynamic require)
3. Configure bundlers and test runners to honor the react-server export condition

Example fix

# before
$ node server.js   # importing react-server-dom-parcel/static throws

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

const args = process.execArgv.join(' ');
if (!args.includes('react-server')) {
  throw new Error('Start this process with --conditions react-server');
}
const RSCServer = require('react-server-dom-parcel/static');

When it happens

Trigger: Importing 'react-server-dom-parcel/static' (directly or transitively) in a Node process started without --conditions react-server, or when a bundler/test runner resolves the conditionless fallback export.

Common situations: Running server code with plain `node server.js`; jest/vitest runners that do not propagate Node execution conditions; deploy scripts or framework configs missing the react-server flag.

Related errors

• The React Server Writer cannot be used outside a react-serve
• The React Server cannot be used outside a react-server envir
• The React Server Writer cannot be used outside a react-serve
• react-dom/profiling is not supported in React Server Compone
• react-dom/server is not supported in React Server Components

AI-assisted analysis of facebook/react@eafeac097b (2026-08-21). Data as JSON: /api/errors/aa063fa59a365f4a. Report an issue: GitHub.