facebook/react · error · 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-webpack/static.js is the fallback './static' entry that throws unless the 'react-server' export condition is active. It guards the static Flight writer so that a mis-configured environment (plain Node, browser, or a bundler without the condition) fails at import time with the exact flag needed, rather than loading server-only code into the wrong runtime.

Source

Thrown at packages/react-server-dom-webpack/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

Start the process with node --conditions react-server
Add 'react-server' to resolve.conditionNames (webpack), conditions (esbuild/vite ssr), or test runner export conditions
Double-check NODE_OPTIONS is present where the import actually executes (containers, cron, process managers)

Example fix

// before
"scripts": {"start": "node server.js"}

// after
"scripts": {"start": "node --conditions react-server server.js"}

Defensive patterns

Strategy: validation

Validate before calling

if (!(process.execArgv.join(' ') + ' ' + (process.env.NODE_OPTIONS || '')).includes('react-server')) {
  console.error('fix: node --conditions react-server');
  process.exit(1);
}

Prevention

Centralize the node start command; do not hand-type it per environment
Include the condition in test, dev, and prod commands identically
CI should run the server entry once as a smoke test

When it happens

Trigger: Importing react-server-dom-webpack/static in any context where the resolver did not apply the 'react-server' condition (plain node, browser bundle, tests).

Common situations: Following RSC demos that use /static without copying the start script's --conditions react-server flag | Tooling (ts-node,tsx, vitest) that resolves exports with default conditions only | Monorepo task runners dropping NODE_OPTIONS

Related errors

AI-assisted analysis of facebook/react@eafeac097b (2026-08-21). Data as JSON: /api/errors/17af201006d2aba9. Report an issue: GitHub.