facebook/react · error · Error

Expected overrideError() to not get called for earlier React

Error message

Expected overrideError() to not get called for earlier React versions.

What it means

React 16.9+ exposes setErrorHandler/scheduleUpdate through injectIntoDevTools so DevTools can force components to error. shouldErrorFiberAccordingToMap is the handler the backend installs; the guard throws if that handler is ever invoked while setErrorHandler was never a function - i.e. the attached React is too old to support toggling errors, so the backend cannot have promised React this behavior.

Source

Thrown at packages/react-devtools-shared/src/backend/fiber/renderer.js:7412

      }
      return inst.data.return;
    } else {
      return devtoolsInstance.data;
    }
  }

  // React will switch between these implementations depending on whether
  // we have any manually suspended/errored-out Fibers or not.
  function shouldErrorFiberAlwaysNull() {
    return null;
  }

  // Map of Fiber and its force error status: true (error), false (toggled off)
  const forceErrorForFibers = new Map<Fiber, boolean>();

  function shouldErrorFiberAccordingToMap(fiber: any): boolean | null {
    if (typeof setErrorHandler !== 'function') {
      throw new Error(
        'Expected overrideError() to not get called for earlier React versions.',
      );
    }

    let status = forceErrorForFibers.get(fiber);
    if (status === false) {
      // TRICKY overrideError adds entries to this Map,
      // so ideally it would be the method that clears them too,
      // but that would break the functionality of the feature,
      // since DevTools needs to tell React to act differently than it normally would
      // (don't just re-render the failed boundary, but reset its errored state too).
      // So we can only clear it after telling React to reset the state.
      // Technically this is premature and we should schedule it for later,
      // since the render could always fail without committing the updated error boundary,
      // but since this is a DEV-only feature, the simplicity is worth the trade off.
      forceErrorForFibers.delete(fiber);
      if (forceErrorForFibers.size === 0) {
        // Last override is gone. Switch React back to fast path.

View on GitHub (pinned to eafeac097b)

Solutions

1. Upgrade the page's React to >=16.9 so setErrorHandler and scheduleUpdate exist in the injected renderer.
2. Hard-reload the page after changing React versions so DevTools re-attaches to the actual renderer.
3. In custom frontends, gate the error-toggle UI on the capability (supportsTogglingError is computed at renderer.js:449-451) and on inspectedElement.canToggleError (renderer.js:6307) instead of calling overrideError unconditionally.
4. Check for duplicate React copies (window.__REACT_DEVTOOLS_GLOBAL_HOOK__.renderers) and remove the stale one.

Example fix

// before (custom DevTools integration)
bridge.send('overrideError', {id, forceError: true, rendererID});

// after - only when the renderer supports it
const renderer = hook.renderers.get(rendererID);
if (typeof renderer?.setErrorHandler === 'function' && typeof renderer?.scheduleUpdate === 'function') {
  bridge.send('overrideError', {id, forceError: true, rendererID});
}

// enable error-override UI only when the renderer supports it (mirrors renderer.js:449-451)
const renderer = hook.renderers.get(rendererID);
const supportsTogglingError =
  typeof renderer?.setErrorHandler === 'function' &&
  typeof renderer?.scheduleUpdate === 'function';

When it happens

Trigger: The error-override flow runs against a renderer older than 16.9: leftover forceErrorForFibers state from a session where a newer React was attached, or a custom frontend calling the overrideError bridge path while the page's renderer lacks setErrorHandler (e.g. after HMR swapped in an older React bundle without a reload).

Common situations: Legacy codebases pinned to React <16.9 (or 15) with a modern DevTools frontend; two copies of React on the page where DevTools bound the older one; downgrading react/react-dom via hot module replacement.

Related errors

• Expected overrideSuspense() to not get called for earlier Re
• Expected overrideSuspenseMilestone() to not get called for e
• Invalid internal instance: ${internalInstance}
• Expected to find root ID.
• Invalid component filter type "${componentFilter.type}"

AI-assisted analysis of facebook/react@eafeac097b (2026-08-21). Data as JSON: /api/errors/b7745110d56fd24f. Report an issue: GitHub.