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.

Screenshot: Install macOS Sierra Update

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 Screenshot: Mac info


4 Answers 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.

  • Hi, you can check above the version. Commented Sep 30, 2017 at 19:55
  • I am upgrading el capitan from 10.11 to 10.12 tried combo update still same issues Commented Oct 30, 2017 at 9:28
  • @shikher.mishra what did you do ? how did worked for you Commented Oct 30, 2017 at 9:29
  • I just did the things mentioned in the above answer. Commented Mar 8, 2018 at 6:54
  • This answer is in a frustrating state. Ran into the same issue, with combo. Asking this again will be a duplicate despite no solution here? What are the requirements? Commented Jul 5, 2018 at 18:36

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.

  • Yes! Thank you for this, also your laptop needs to be on adapter power for the encryption to keep running. Thanks!
    – DJTano
    Commented Apr 8, 2020 at 21:17

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.

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