I just did some testing. Take a look at your line vty configuration.
If there's a transport input protocol defined, like 'transport input ssh' the vty lines will not accept http connections, hence the 'out of lines' error.
If you change this into 'transport input all' it'll work.
When I said I did nothing for a couple of days, I meant I did do a reboot. As I was setting up my switch I had probably set the transport input to ssh and didn't save. So after the reload it was set to transport input all again.
This does leave an issue, that telnet access to the switch is possible and I don't like that. You can of course block this by using access lists.
I also wonder why there's no possibility to do 'transport input http'
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...