Launching the Hub produces the error
The Qlik Sense Management Console is reachable and it displays no Engine errors. The Qlik Sense Engine is up and running.
This happens on a Central node, and there is no issue with port 4900 (as detailed in article Proxy RIM node error from HUB "the proxy is waiting for a new session).
If you have just patched to a more recent version of Qlik Sense, then you may also need to try Recreating the Qlik Sense Root Certificate (Root CA) as NodeJS has newer requirements for the certificate.
Proxy RIM node error from HUB "the proxy is waiting for a new session"
Should the issue persist, please contact Qlik Support at support.qlik.com.