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

The turbopack Flight server entry throws at import time unless the react-server Node condition is active. The export map swaps this stub for the real server runtime only when Node resolves conditions include react-server, preventing the serialization runtime from loading in client contexts.

Source

Thrown at packages/react-server-dom-turbopack/server.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. Launch with node --conditions react-server wherever the server entry loads
2. Scope server-entry imports to react-server conditional branches only
3. Verify test/bundler config propagates react-server so the real entry resolves

Example fix

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

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

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

When it happens

Trigger: import/require of react-server-dom-turbopack/server in a Node process started without --conditions react-server, or via a bundler that resolved the fallback export.

Common situations: Plain `node` invocations of server entrypoints; CI scripts and test runners that do not forward Node conditions; framework configs that dropped the flag after an upgrade.

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
• Use react-server-dom-turbopack/client instead.
• Use react-server-dom-turbopack/client instead.

AI-assisted analysis of facebook/react@eafeac097b (2026-08-21). Data as JSON: /api/errors/f00592ddc68eb65d. Report an issue: GitHub.