Use OS X Combo Updates to Correct Installation Problems

Try this quick fix for a faulty system update or corrupt system files

OS X El Capitan desktop

Apple routinely releases updates to macOS and OS X that are available through the Software Update process or the Mac App Store, depending on the version of macOS or OS X you use. These software updates usually provide the simplest method for ensuring your Mac's operating system is kept up to date. Still, you may encounter a problem.

Information in this article applies to macOS Catalina (10.15) through OS X Mountain Lion (10.8).

When a System Update Goes Wrong

If your Mac freezes, loses power, or otherwise prevents an update from completing, you end up with a corrupt system update. This may manifest as a simple instability with occasional freezes or the system or applications lock up. In the worst-case scenario, you may have problems booting, forcing you to consider reinstalling the OS.

Another problem is related to Apple's incremental approach to updates. Since Software Update only downloads and installs system files that need to be updated, some files may be out of date with respect to other system files. This can result in infrequent system or application freezes or the inability of an application to launch.

A problem with a software update is infrequent, and most Mac users never see it. However, if you have unexplained issues with your Mac, a defective software update could be the culprit. Eliminating it as a possibility is easy to do with the help of a combo update, which is a regular update on steroids.

Using the macOS and OS X Combo Update

You can use a macOS or OS X combo update to bring your system up to date and, in the process, replace most of the key system software files with the most current versions included in the updater. Unlike the incremental approach used in the Software Update system, the combo update does a wholesale update of all affected system files.

A combo update only updates operating system files; it doesn't overwrite any user data. Even so, it's a good idea to back up your data before applying any system update.

The downside to the combo updates is that these updates are huge. The current macOS Catalina combo update download is just shy of 4.6 GB in size.

To apply a macOS or OS X combo update, locate the file on the Apple website, and download it to your Mac. Then run the update to install the newest system on your Mac. You can't use a combo update unless the baseline of that version of the operating system is installed. For example, the OS X 10.10.2 combo update requires that OS X 10.10.0 or later is installed. Likewise, the OS X 10.5.8 combo update requires that OS X 10.5.0 or later is installed.

Locate the macOS or OS X Combo Update You Need

Apple keeps all the OS X combo updates available on the Apple support site. One way to locate the correct combo update is to go to the OS X Support Download site and search for it. Click the link for the version you need. Select the combo update, which is not the same file as a regular update or client update. If you don't see the phrase combo update, it's not the full installer.

Here are quick links to the combo updates for the last eight versions of macOS and OS X:

OS X Version Download page
macOS Catalina 10.15.3 Combo Update
macOS Catalina 10.15.2 Combo Update
macOS Mojave 10.14.6 Combo Update
macOS Mojave 10.14.5 Combo Update
macOS Mojave 10.14.4 Combo Update
macOS Mojave 10.14.3 Combo Update
macOS Mojave 10.14.2 Combo Update
macOS High Sierra 10.13.6 Combo Update
macOS High Sierra 10.13.5 Combo Update
macOS High Sierra 10.13.4 Combo Update
macOS High Sierra 10.13.3 Combo Update
macOS High Sierra 10.13.2 Combo Update
macOS Sierra 10.12.6 Combo Update
macOS Sierra 10.12.5 Combo Update
macOS Sierra 10.12.4 Combo Update
macOS Sierra 10.12.3 Combo Update
macOS Sierra 10.12.2 Combo Update
OS X El Capitan 10.11.6 Combo Update
OS X El Capitan 10.11.5 Combo Update
OS X El Capitan 10.11.4 Combo Update
OS X El Capitan 10.11.3 Combo Update
OS X El Capitan 10.11.2 Combo Update
OS X Yosemite 10.10.5 Combo Update
OS X Yosemite 10.10.4 Combo Update
OS X Yosemite 10.10.3 Combo Update
OS X Yosemite 10.10.2 Combo Update
OS X Mavericks 10.9.5 Combo Update
OS X Mavericks 10.9.4 Combo Update
OS X Mavericks 10.9.3 Combo Update
OS X Mavericks 10.9.2 Combo Update
OS X Mountain Lion 10.8.5 Combo Update
OS X Mountain Lion 10.8.4 Combo Update
OS X Mountain Lion 10.8.3 Combo Update
OS X Mountain Lion 10.8.2 Combo Update

The combo updates are stored as .dmg (disk image) files that mount on your Mac the same way as removable media, such as a CD or DVD. If the .dmg file doesn't mount automatically, double-click the downloaded file.

After the .dmg file mounts, you see a single installation package. Double-click the installation package to start the install process and follow the on-screen prompts.