I wouldn't be using the WebGUI to configure a switch. Drop back to a console connection and then try again.If you're partially configuring the switch and then attempting to configure the switch from the GUI then you'll need to set a username / passwo...

Have you had any luck with this?   I myself am trying to reset all the configurations to factory so I can start from scratch.   I'm at Everest 16.6.5 of my Catalyst 9300.   If anyone can help, I'd appreciate.