Screen Sharing broken after Security Update 2018-002 10.11.6

I had this same problem on two machines, a Mac mini Server, and an iMac. After I did the Security Update 2018-002 for 10.11.6 both stopped working for Screen Sharing or VNC connections. Restarting a couple of times didn't help.

However, after the Security Update, a Remote Desktop Client Update 3.9.3 was offered. This didn't fix the problem right way, but after a restart both Apple Screen Sharing and VNC worked again! Both machines.

I ran into this issue when remotely updating several computers running 10.11.6 with ARD Agent 3.8.5. After installing Security Update 2018-002 10.11.6 I was unable to connect via screen sharing (including VNC). All other remote access functionality was in tact though so I could SSH into the machines. From there it was just a matter of running softwareupdate -ia from the command line which installed Remote Desktop Client Update (3.9.3). If you want to first verify the update is available run softwareupdate -l.

I discovered I lost Screen Sharing after updating to 2018-002 on two machines running El Capitan. The Remote Desktop Client update to 3.9.3 update worked for me, but I had to install it on both machines for it to come back. It seems like the 3.9.3 update should have been included in 2018-002.

Cheers.

It turns out that that the 2018-002 10.11.6 update is actually downgrading the ARD client. Prior to the update the computer reports ARD client version 3.9.3. After the update it shows ARD client 3.8.5.

Before Update

After Update

In my case it happen like that with "File Sharing". After many tries I solved by activating and deactivating "Windows File Sharing" in the options menu.

You don't even need ssh/cli -- if you download the .dmg and open it on your machine, then you just use the ARD "Install" button and drag the pkg file over and run the install on it. As far as I can tell the ONLY thing that is broken is the actual Observe/Control screen sharing, all of the other functions of ARD are just fine.

Thanks Troy, your solution worked for me to. I had just applied the security update to my El Capitan Machine and was no longer able to screen share from my Sierra iMac. Updating the Remote Desktop Client and a re-boot as per your post fixed it for me. Thanks for sharing your solution.

You rock! That was the missing part - performing the necessary update via SSH and CLI when not able to connect per ARD solved the "not able to connect problem". No reboot necessary.

This has happened to us as we have dozens of El Capitan macs all managed via ARD. We downloaded the dmg for ARD client 3.9.4 and do a remote install after the security update. A couple of things we have concluded:

-- Before running the security update, which we run via the AppStore, the system does not offer an ARD client update when the client version is old. After running the update, AppStore shows the 3.9.4 update available.

-- When running the update while connected, it gets to the reboot and ARD comes up "Reconnecting..." but it never connects. When looking in ARD server after the update, to every appearance it looks like you should be able to observe or control the client. It reports out all of the versions, who is logged in, what application is on top. You can copy files, install software, run unix commands. But the "Connecting..." panel comes up and it never connects.

-- The client ARD version shows (on the ARD server screen) as 3.8.5 after the security update.

-- When connected in some other way (TeamViewer in my case) after the Security Update is applied, launching AppStore shows the 3.9.4 ARD update that wasn't there before. When installing the update, the instant it finished installing my ARD session connected.

-- One of my colleagues installed the security update on a machine that was actually still at 3.8.5, and he was NOT locked out like on all of the machines that started with some version higher than 3.8.5.

We are speculating that

-- ARD client 3.9.4 won't run without the security update

-- versions of ARD after 3.8.5 but before 3.9.4 will not run with the security update

-- the security update is attempting to downgrade ARD client to 3.8.5 but somehow bungles it enough that Observe & Control are broken. But since everything else works you can use ARD to update the ARD client to 3.9.4 when it is in this state. (This has the signs that it should have been worked so that ARD client updated to 3.9.4 as part of the security update, but there was something wrong, or they ran out of time to get it to QA, etc. The downgrade to 3.8.5 is a hack and it's broken.)