SIGX100 · Render target not found#

Dev message

Render target "#app" not found.

Suggestion

Make sure the element exists in your HTML: <div id="app"></div>

What happened#

render() was given a selector that matched nothing in the document. The selector itself is usually right — the element just isn't there yet at the moment the query runs.

Three things cause that, in rough order of likelihood:

  • The script runs before the element is parsed. A classic <script> in <head> executes while <body> is still empty.
  • The id in the markup and the selector have drifted apart — a typo, or one was renamed.
  • The element is created later by other code that hasn't run.

Fix it#

Make sure the target exists in your HTML:

HTML 
<body>
    <div id="app"></div>
    <script type="module" src="/src/main.ts"></script>
</body>

Keeping the script tag after the element — or marking it type="module", which defers by default — is what guarantees the element is parsed before the query runs.

You can also pass the element itself rather than a selector, which sidesteps the timing question entirely:

TypeScript 
const target = document.getElementById('app');
if (target) render(<App />, target);