I have tried to download and update my iMac from 10.11.1 to 10.11.2 (this update is for both Recovery Update 1.0 and El Capitan 10.11.2). My MBP updated fine with no issues. SIP (rootless) is disabled on both my iMac and MBP. I did not have to re-enable SIP to update the MBP, it continues to be disabled and the OS (and third-party app) work fine. My iMac will attempt the update by first prompting me for a restart (nothing unusual there). Then it goes to a black screen and hangs. The mouse cursor can still be moved around using either the BT mouse or the Apple Trackpad. But it stays stuck on that black screen, nothing else happens. I left it like that for over an hour, hoping it would finish whatever processes were at work under the hood, but it won't even sleep (the fan hums away, but the screen does turn off, as I have it set in Energy Prefs). I also cannot boot to Recovery Drive. I was going to do this to check the disk. Anyone have a similar problem? Any idea why I cannot update? The HD is new, only five dos. old. I have already run updates while this HD has been installed. UPDATE: I downloaded the offline installer and it too results in the same problem. I can't get the iMac to update. I did notice something weird - I can still connect to the iMac from my MBP...I can access the files and also Screen Sharing (but it shows a black screen, and I can move the cursor around).