Q: macOS Sierra installation (from El Capitan) fails with "Internal error" message
Tried updating to macOS Sierra and it looked like everything was fine, but at the every end of the process it wouldn't finish the install. Sierra downloaded OK, and when I clicked install it went through a process for 15-30 minutes, restarted, and then looked like it was finishing the install for a few minutes. But then I got the error-like message (a light grey window on a dark grey screen, with a round Sierra icon near the top):
"macOS could not be installed on your computer.
An internal error has occurred.
Quit the installer to restart your computer and try again
[Restart Button]"
I have a Macbook Pro Retina Mid 2012 with a 2.6 GHz Intel Core i7 processor, NVIDIA GeForce GT 650M 1024 MB graphics, 16 GB 1600 MHz DDR3 RAM, and an APPLE SSD SM768E flash hard drive. I've run Disk Utility, and it says everything is fine. I've tried different approaches, multiple times, but no matter what I try, I can't seem to install the new macOS Sierra. I've even wiped my entire computer and started from scratch, installing a clean OS X 11 (El Capitan) and then trying to install Sierra, but still it doesn't work. This is making me think it's possibly an issue with my App Store account? But since I was logged in, I'm not sure what that could be. Or maybe it's hardware related? I dunno. Even the Apple Sr. Advisor I was talking with on the phone was stumped.
Super frustrated, definitely would love some guidance, thanks!
MacBook Pro with Retina display, OS X El Capitan (10.11.6), null
Posted on Sep 21, 2016 7:44 PM
I found a solution to my problem thanks to this thread: Re: Can't upgrade to OS Sierra
It seems that - in my case at least - the install was confused by the "&" symbol in the name of the install volume. My install volume was called "OS & Apps". I renamed it to "Startup" and ran the install again and it succeeded.
This (to my naive eye) looks like a problem with quoting or escaping in a shell script executed during the install. So if you are having this problem, take a look at the name of your install volume and if you have any symbols try renaming the volume and install again. One poster above solved the problem using a fresh install but I wonder if the install volume was renamed along the way and this was the true fix.
Cheers
..Mark..
Posted on Sep 25, 2016 3:26 PM

