I've run into this case myself and it took me a second to realize what was going on. When you set jupyter to use a remote server it's easy to forget that setting was set, particularly as you can set that setting per workspace. If you then shutdown that server and try to connect again instead of a reasonable error you get that ECONNREFUSED message that has plagued us. You do see the server name in that message, but it's not clear that you still have the remote setting on. We need to make this more clear to customers as this could be the cause of some ECONNREFUSED messages.