Error "TypeError: Cannot read property '$server' of null"

Sometimes I got that error in my screen but in my console don’t show anything. anyone know what is?

tks
18450037.png

When you say that there is nothing in your console, are you referring to the server’s console, or the browser console? I would expect to see an error logged to the browser console.

Are you using $server to call the server from the client? If not, the error will be in one of the Vaadin components.