- Start CE demo webapp
- Log in into admincentral
- Interact with UI (e.g. click a find bar result)
Progress bar is pending infinitely (most of the times, although this should be tested repetitively).
Refresh the browser tab.
This is caused by UI#push calls before the push connection is established (in our case findbar results).
Although vaadin has code to handle these pending pushed, this causes the freezing.
https://github.com/vaadin/framework/blob/e30226a19564c6ee77064e5178a7665554d57466/server/src/main/java/com/vaadin/server/communication/AtmospherePushConnection.java#L256 (commenting out this line fixes the issue)