@gorelov @krivopustov
Hello guys, I dont think that it is harmless.
It is OK in DEV. No problem ever.
But in PROD on AWS EC2 AL2023 instance the problems begun… 
At the same monment:
UI:
Communication problem
Pay attention to any unsaved data, and click here to continue.
Invalid JSON from server: 1|X
WebDeveloper Tools Console in Edge:
vaadinPush.js?v=8.14.3-4-jmix:1 Websocket closed, reason: Connection was closed abnormally (that is, with no close frame being sent). - wasClean: false
log @ vaadinPush.js?v=8.14.3-4-jmix:1
warn @ vaadinPush.js?v=8.14.3-4-jmix:1
ax.onclose @ vaadinPush.js?v=8.14.3-4-jmix:1
appliation log on server:
2024-02-07 20:30:15.312 WARN 61047 — [nio-8080-exec-7] org.atmosphere.util.IOUtils : More than one Servlet Mapping defined. WebSocket may not work org.apache.catalina.core.ApplicationServletRegistration@fda1a7a