Method showPopup is not supported in version 6.0

Не детектит telegram библиотеку с документацией, хотя source верный:

<script src="https://telegram.org/js/telegram-web- 
app.js"</script>
<script>
var WebApp = window.Telegram.WebApp;
WebApp.showAlert(`Welcome, @${WebApp.WebAppUser}.`);
</script>

Ошибки:

Method showPopup is not supported in version 6.0
telegram-web-app.js:1784 Uncaught Error: WebAppMethodUnsupported
at WebApp.showPopup (telegram-web-app.js:1784:13)
at WebApp.showAlert (telegram-web-app.js:1883:12)
at index.html:59:12