Internal error popup

Hi. What is the right way to show custom internal error popup?

Custom like changed text? https://vaadin.com/forum/thread/17782105/system-messages

Custom like totally different? Not supported

Or do you mean as in showing an error popup about something that went wrong in your app, where the app still works but you want to inform the user about an unexpected error state? In that case I would go with a modal Dialog.

No, I was thinking about Vaadin internal error. Thanks.