vercel/ai · error

Unsupported React version.

Error message

Unsupported React version.

What it means

InternalAIProvider runs on the client and relies on React's `use()` hook (React 19 / the `use` proposal). The SDK checks `'use' in React` and throws if the hook is missing, because the client context streams AI state through `React.use`. Older React versions without `use` cannot drive the provider.

Source

Thrown at packages/rsc/src/shared-client/context.tsx:31

  InternalAIProviderProps,
  ValueOrUpdater,
} from '../types';

const InternalUIStateProvider = React.createContext<null | any>(null);
const InternalAIStateProvider = React.createContext<undefined | any>(undefined);
const InternalActionProvider = React.createContext<null | any>(null);
const InternalSyncUIStateProvider = React.createContext<null | any>(null);

export function InternalAIProvider({
  children,
  initialUIState,
  initialAIState,
  initialAIStatePatch,
  wrappedActions,
  wrappedSyncUIState,
}: InternalAIProviderProps) {
  if (!('use' in React)) {
    throw new Error('Unsupported React version.');
  }

  const uiState = React.useState(initialUIState);
  const setUIState = uiState[1];

  const resolvedInitialAIStatePatch = initialAIStatePatch
    ? (React as any).use(initialAIStatePatch)
    : undefined;
  initialAIState = React.useMemo(() => {
    if (resolvedInitialAIStatePatch) {
      return jsondiffpatch.patch(
        jsondiffpatch.clone(initialAIState),
        resolvedInitialAIStatePatch,
      );
    }
    return initialAIState;
  }, [initialAIState, resolvedInitialAIStatePatch]);

View on GitHub (pinned to 69428b1f8b)

Solutions

1. Upgrade to React 19 (or the Next.js version that ships it): `pnpm add react@latest react-dom@latest`
2. Upgrade Next.js to a version compatible with React 19 if applicable
3. Run your package manager's dedupe/install to remove stale React 17/18 copies (`pnpm install`, `npm dedupe`)
4. Check `require('react').use` / `'use' in React` in your app to confirm the resolved version

Example fix

// before (package.json)
"react": "^18.2.0",
"react-dom": "^18.2.0"
// after (package.json)
"react": "^19.0.0",
"react-dom": "^19.0.0"

// run once at app entry (client)
if (typeof React === 'undefined' || !('use' in React)) {
  throw new Error('This app requires React 19+ (with the `use` hook) for ai/rsc');
}

function supportsReactUse(react: typeof React): react is typeof React & { use: unknown } {
  return 'use' in react;
}

try {
  root.render(<AI>{children}</AI>);
} catch (err) {
  if (String(err).includes('Unsupported React version')) {
    console.error('Upgrade react/react-dom to ^19');
  }
  throw err;
}

When it happens

Trigger: Rendering the client-side `<AI>` provider with React 17 or React 18 without the `use` experimental/stable hook available; pinning an old `react`/`react-dom` version while using a recent `ai` package; package-manager dedupe resolving an older React copy.

Common situations: Upgrading `ai` but not `react`/`next`; a stale lockfile keeping React 18.x installed; using `ai/rsc` outside Next.js canary versions that shipped React 19 features.

Related errors

• `useSyncUIState` must be used inside an <AI> provider.
• ${method}: Value stream is already closed.
• ${method}: Value stream is locked and cannot be updated.
• .append(): The current value is not a string. Received: ${ty
• .append(): The value is not a string. Received: ${typeof val

AI-assisted analysis of vercel/ai@69428b1f8b (2026-08-30). Data as JSON: /api/errors/b3ca216a2aa4f902. Report an issue: GitHub.