I have been updating the macOS from 10.12.4 to 10.12.6 . For this I have downloaded the macOS dmg file from the Apple website. But when I go on for installing the macOS then I see this error.
I have around 100GB of space but its still not updating the OS. What should I do about it. I need to install "Xcode" from the App Store but when I go on for installing it gives me the error that it needs the OS update to be 10.12.6 How can I fix this up?
The version I am working on is 10.12.4
In my experience, downloading and installing the Combo Update sometimes works when the Delta update fails. Please edit your question to indicate the specific Mac model you are working with.
I just bought a reconditioned MacBook Air running macOS High Sierra 10.13.4 and as I wanted to upgrade to macOS High Sierra 10.13.6, I ran into the same problem. I tried everything and was about to give up, until I stumbled the following page:
and realized that FileVault was still encrypting my hard disk and that was blocking any macOS update.
In very simple words. You need update .dmg file which is COMBO.
Apple has 2 types of updates Delta and Combo. Delta. You can only update Version +1. Ex . If you have 10.15.2 and you download 10.15.5, Mac will provide this error but it will allow if you download 10.15.3.
Combo. It contains all delta + new update and you can download and install without an issue. Delta kind of check doesnt apply for combo
Since you have the full installer, I would make a bootable USB installer if you have a spare 8 GB drive lying around.
Search Apple or this site for the createinstallmedia command that you can run from the command line (terminal.app) and make the full installer into a bootable image.
Then restart with the USB and hold option key. This works when your system isn’t bootable at all and much better than just a combo updater or the install app on your main OS.
