macOS Sierra update can't be installed on this disk.This volume does not meet the requirements for this update

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

Solution 1:

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.

Solution 2:

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:

• https://technology.siprep.org/waiting-for-filevault-encryption-to-finish-to-install-macos-updates/

and realized that FileVault was still encrypting my hard disk and that was blocking any macOS update.

Solution 3:

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