Remotely upgrading to El Capitan broke Screen Sharing We have a remote Mac Mini acting as a build server that we use Screen Sharing to connect to and remotely manage.

Well I recently upgraded this box to El Capitan and now Screen Sharing won't connect to it at all.

I've upgraded the OS remotely before and never ran into a problem. Is there any way to connect to this box and get screen sharing working or am I S.O.L.? I can ping it, but I can't seem to do anything else (file sharing, ssh, screen sharing).

Update: I did a port scan on the server and it can't find any open ports. I guess that pretty much settles it then. I still don't understand how upgrading and rebooting the box could have so completely bricked it. I mean did Apple really not remote upgrading a possibility?

I'm half picturing some "Welcome to El Capitan, just a few screens to click through before you get your computer back" dialog to be sitting on the screen right now. 

Update 2: So we got this resolved, but it looks as though something may have gone wrong during the upgrade process as our IT guy says it wasn't responsive when he plugged a monitor into it. He had to reboot the machine before it would respond. Anyway just wanted to give a heads up to others.
The three ways to connect are Apple Remote Desktop, ssh and remote Apple Events. If you have one of those enabled, you can kickstart screen sharing with a command line tool:

   sudo /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart -activate -configure -access -on -restart -agent -privs -all


See these for more details:


Restart Screen Sharing Service on Mac mini Server
Remotely turn on screen sharing
activating screen sharing remotely


If not, you will have to have the machine shipped to a human or a human shipped to the machine to take local corrective action and diagnose the failure.