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.

Solution 1:

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.

Solution 2:

eAfter a local update to El Capitan, I could also not get the Screen Sharing (VNC://) to work. Not with ARD or the Screen Sharing Client. Rebooting and re-set the Sharing setup did not work. I got it back to work with this Shell commands (it will work local via Terminal or remot via SSH): (put in YOUR-SHORT-USERNAME eg: admin)

 sudo /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart -configure -allowAccessFor -specifiedUsers
 sudo /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart -configure -access -on -privs -all -users YOUR-SHORT-USERNAME
 sudo /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart -restart -agent
 sudo /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart -activate