When trying to connect by using the SSH protocol, sometimes the NoMachine client issues the following message:

The session negotiation failed.

Error: NX access is disabled

Possible reasons for getting this message are:

- The server  has been stopped, i.e. it doesn't accept new connections.

Be sure that the server is up and running, you can start it from the NoMachine monitor in your system tray: select 'Show the service status' and click on 'Start the server'.

- The server  has been shutdown, i.e. all NoMachine services, included the Monitor in the system tray, have been stopped.

Be sure that all NoMachine services are up and running, you can start them from the NoMachine User Interface: click on 'Settings' to open the Preferences GUI and then click on the 'Server status' icon at the bottom of the panel to open the Service Status panel. Click on 'Start the server'.