How to Fix “The macOS Installation Couldn’t Be Completed” Error?

Your Mac automatically looks for new software updates every week and downloads them. So you get a notification whenever a new update is ready. This way, it stays up to date on the latest security patches and bug fixes.

However, there are instances where, after downloading an update or updating the macOS to the latest version, you get an error message – “The macOS installation couldn’t be completed.” There can be various causes, such as a corrupted installer, disk errors, insufficient storage space, and more.

After receiving several user queries and thoroughly analyzing this error, we have come up with a list of solutions to help fix this issue.

But let’s first understand the reasons behind this error.

Why Does this Error Occur?

A macOS installation could fail for a variety of reasons. The most common causes that prevent macOS from completing installation are:

• Not enough free space on your Mac.
• The macOS installer file has been corrupted.
• There are issues with your Mac’s startup disk.
• Your Mac’s hardware is not compatible with the new update.
• The installation pathis missing or damaged.

Irrespective of what’s causing the installation error on your Mac, you can resolve it by following the troubleshooting methods outlined in this post. But before moving on to the solutions, let’s cover the basics.

Preparatory Steps Before Resolving macOS Installation Issues

You must protect your Mac from inadvertent data loss while resolving the macOS installation error. Ensure the following before troubleshooting the error:

Verify Your Mac’s Compatibility

Check if the latest macOS version is compatible with your system before proceeding with the troubleshooting solutions.

Step 1: Launch the App Store on your Mac and search for the specific version of macOS you intend to install (e.g., ‘macOS Ventura’). 

Step 2: Click on the application to view its details in the App Store.

Step 3: Navigate to the Information area by scrolling down.

Step 4: In the Compatibility section, you’ll see whether this macOS upgrade suits your device.

Backup Your Mac’s Data on Time Machine

OS updates tend to alter your essential system files and directories. Therefore, backing up your Mac before a significant update is highly recommended.

Mac’s built-in backup feature, Time Machine, takes incremental backups of your data to protect it from unforeseen loss. Hence, before proceeding, connect an external drive to your Mac and use Time Machine to back up your files.

Boot Your Mac in Safe Mode

Safe Mode prevents certain applications, including the macOS installer, from automatically running each time your computer boots up. Launching your Mac in Safe Mode lets you get out of startup loops and prevents unnecessary programs from operating in the background.

To start your Mac in safe mode, follow the instructions below:

Safe Mode on the Intel chip Mac

Step 1: Reboot your Mac and immediately press and hold the Shift button. 

Step 2: After your computer turns on or you see the Apple logo, release the Shift key. 

Step 3: You should see the login window; choose the Safe Boot option.

Safe Mode on the Apple Silicon-based Mac

Step 1: Shut down your computer completely. 

Step 2: Hold the power button until you see the startup screen on your Mac. 

Step 3: Select a startup disk and press Shift on your keyboard.

Step 4: Click Continue in Safe Mode.

Ways to Fix “The macOS Installation Couldn’t Be Completed” Error

After confirming that your device meets the requirements for the latest macOS version, initiating Safe Mode on your Mac, and securing your data with a backup, you are now ready to follow the troubleshooting methods provided below.

Method 1: Restart Your Mac and Reinstall the Update

Sometimes, you only need to restart your Mac to fix macOS errors. Go to the Apple menu in the upper left corner of your screen and click on Restart from the drop-down menu. You can also press and hold the Power button to perform a force shutdown.

However, do not attempt a force shutdown while the installation is still in progress, as it may corrupt operating system files.

Method 2: Check the Date and Time Settings

Incorrect date and time settings may cause issues when trying to connect with Apple’s recovery server, responsible for providing updates. Hence, this could be a reason for incomplete update installations.

Follow these steps to correct the date and time settings on your Mac:

Step 1: Click on the Apple logo and navigate to System Preferences (or System Settings).

Step 2: Select Date & Time. 

Step 3: Click the lock icon and enter your password to authorize changes. 

Step 4: Select the option to Set a date and time automatically. 

Step 5: Finally, attempt to install macOS again to check if the issue has been resolved.

Method 3: Ensure There’s Enough Space on Your Drive

For a standard Mac installation, the installer takes up about 4 to 5 GB of disk space. However, there’s a catch: your system requires an additional 20 GB of free storage to proceed. The macOS installer requires this extra space to decompress files and folders, and without this additional free space, the installation process can not be completed.  

Follow these steps to check the available space on your Mac:

Step 1: Go to the Apple menu.

Step 2: Select About This Mac.

Step 3: Click Storage (or More Info > Storage).

Step 4: Click on Manage Storage (or Storage Settings) to identify what is occupying the most amount of space.

Step 5: Follow the recommendations to get additional storage on your Mac.

Method 4: Reset the PRAM and NVRAM Settings

PRAM and NVRAM both refer to non-volatile RAM, which is basically memory or storage that cannot be altered. It stores a variety of information and preferences, including display settings, sound volume, screen resolution, etc.

There could be errors in your PRAM or NVRAM that may hinder the macOS installation. Nevertheless, resetting these settings without affecting your data is very simple: 

Step 1: Simply restart your Mac and hold the Option + Command + P + R keys simultaneously. 

Step 2: Continue to press these keys until a second Apple logo appears or you hear a second starting sound.

By this time, the reset would be complete.

Method 5: Download a New Copy of the macOS Installer

If you’re repeatedly facing the error, it is likely that your macOS installer has become corrupted. In this case, it’s a good idea to discard the current installer and replace it with a new one. It is recommended if you download it directly from Apple’s support page so that you get the complete installer package instead of a compressed version available via System Preferences or the App Store.

Method 6: Perform First-aid on Your Startup Disk

Still experiencing issues with your macOS installation process? There may be disk authorization or fragmentation bugs on your startup disk. Fortunately, many of these errors can be resolved by utilizing the pre-installed Disk Utility app on macOS.

To utilize Disk Utility, proceed with the following steps:

Step 1: Go to the Applications folder.

Step 2: Look for the Utilities folder, and launch the app.

Step 3: From the sidebar, locate your Mac’s startup disk (labeled as Macintosh HD), and click on it.

Step 4: Next, select First Aid.

After you run First Aid, Disk Utility will initiate a scan of your Macintosh HD for any bugs and automatically fix them.

Method 7: Reinstall macOS in Recovery Mode

If the previous solutions did not work, you may need to reinstall the operating system. You can do it through macOS Recovery, but the process varies between Intel-based Mac and Apple Silicon-based devices. 

Intel chip Mac:

Step 1: Restart your computer and hold down the Option + CMD + R keys until you hear the startup noise or see the Apple logo appear. 

Step 2: Release the keys at this point. 

Step 3: To reinstall the most recent version of macOS using macOS Recovery, select Reinstall macOS and be prepared for the installation process to take a while, as the new software must be downloaded before installation can begin.

Apple Silicon-based computer:

Step 1: Shut down your Mac. 

Step 2: Hold Mac’s Power button until the startup options appear on your screen.

Step 3: Click on Options and then Continue to proceed.

Method 8: Erase the Startup Disk and Reinstall macOS

When encountering installation-related errors, the final troubleshooting method is to erase the startup disk and reinstall the macOS. Once a new macOS version is installed, you can restore all your data from the Time Machine backup.

Here’s how to erase the startup drive on a Mac:

Step 1: Go to the Applications folder, look for the Disk Utility software and launch it.

Step 2: Select the startup drive and choose Erase from the top menu.

Step 3: When prompted, click the Erase option to continue.

Now you can install the updated version of macOS for a fresh start.

If you’ve lost any significant data following any of the above steps, you can use a Mac File Recovery Software – Stellar Data Recovery for Mac to retrieve your lost data. This tool can help you recover documents, images, videos, emails, and other items on your Mac in just a few simple steps.

Free Download

Summing Up

Various factors may lead to “the macOS installation couldn’t be completed” error. You can try the solutions mentioned in this guide to resolve the issue. If nothing works, you’ll have to erase and reinstall the macOS on the startup drive. Later, you can use the Time Machine backup to recover your data.

However, if you don’t have a backup and accidentally erasing the data on your Mac, use a reliable data recovery tool, such as Stellar Data Recovery for Mac, to restore the lost files.

Was this article helpful?

YES0

NO

About The Author

Vishal

Vishal is a data recovery expert @Stellar. He addresses data loss scenarios on a Mac. He intends to help people solve their macOS problems. Besides, Vishal prefers to read about astronomy and autobiography, and his favorite is Steve Jobs - The man who thought different written by Karen Bluementhal.