JS Error /rest/sitemaps/events cannot be reached


i upgraded from Openhab1 to 2 and when i open the basicui i get the following JS Error in smarthome.js:1:18257. I think this is why the UI doesn’t show value updates. So if i close a rollershutter, the percentage remains at x%. But if i reload the page, the percentage shows the correct value.

Firefox kann keine Verbindung zu dem Server unter http://xxx/rest/sitemaps/events/xxx?sitemap=xxx aufbauen.

Is there anything i need to configure to enable event updates on the UI?