App did not start

This usually happens on school PCs when an old browser cache still points to a previous update, or when the browser is too old for the IDE. Clear the stuck files and reload — you will not lose account data.

Recommended: Google Chrome or Microsoft Edge (Chromium) version 70 or newer. On old Windows PCs, install Chromium Edge — not Internet Explorer. Or press Ctrl+Shift+R for a hard refresh.