How to fix macOS installation couldn’t be completed error?


Did you face this error like “The macOS installation couldn’t be completed” while updating your Mac? No need to worry, it’s a common error that many users have reported facing. The error messages read like this, “If you continue having a problem installing macOS, the installation log may help you diagnose the problem. To save the log, click Save log. To start installing macOS again, click Restart. To start up your computer using a different disk, choose Startup Disk from the Utilities menu.” read this article to learn how to fix macOS installation couldn’t be completed error.

Why macOS installation couldn’t be completed?

There are a few reasons behind this error which make us ask “why can’t I update my mac”. One of the main reason is insufficient space in the Mac that lead to this error. The latest update in Mac comes with Catalina which is almost 8GB and for that users need at least 20GB of space. If enough space is not available on your Mac, macOS installation couldn’t be completed. Another reason could be from Apple itself, as once they roll out a new update, millions of Mac users will be flooding to update it. This could result in the server down for the apple update and result in incomplete updates or frozen screens. Nonetheless the reasons, we have a solution to this issue which can solve the problem right away. Read further to learn more about how to fix macOS installation couldn’t be completed error.

How to Fix macOS Installation Couldn’t be Completed?

If macOS could not be installed on your computer and you are facing issues regarding installation, then here are some of the methods to fix the macOS Installation Couldn’t be Completed error.

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Note: Before using any of the methods given below, we advise our reader to take a full backup.

Start Mac in Safe Mode

When users face this issue, they will be presented with four options, shut down, restart, save log, and view log. Even with repeated restart, they will still face Catalina update problems. But with safe mode in Mac, they can start over and solve this issue right away. Here is how to start Mac in safe mode.

  • Shut down your Mac
  • Now restart your Mac
  • Once the Mac started, press and hold the Shift key, some Mac starts with the opening sound, press the shift key when you heard the sound
  • Once you see the grey apple logo, release the Shift key

Now check for any issue on your Mac in safe mode. This safe mode allows users to bypass startup and other apps and users can fix any issue from here. This will take longer than usual to start your Mac. if the issue still persists, then try repairing the disk.

Mac Disk Repair

In order to run disk repair on Mac, try this method.

  • Start your Mac, or restart it
  • Now hold the command button and R
  • Until you see the Apple logo, hold those button and then release it
  • After that, Mac OS utility will launch
  • Go to disk utility and continue 
  • After that, run first aid

This will check the disk and provide relevant information regarding any error. If the error macOS Installation Couldn’t be Completed is the reason behind any error with the disk, then it will show up in disk repair. If this won’t solve your issue, then try another method.

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Reinstall macOS

This is the final solution to solve this error. If everything fails, then reinstalling Mac from the scratch is the only way to move forward. Here is how to Reinstall macOS. 

  • Restart your Mac and hold the command button and R
  • When you see the Apple logo, release both buttons
  • Now go to Mac utilities 
  • After that select reinstall macOS

After that follow the instruction and reinstall Mac which will solve this issue completely. Before you reinstall Mac OS, make sure to check few things first which can help with macOS Installation Couldn’t be Completed issue.

  • Check for the Apple server down at the official Apple system status, if you find the server is down, then wait for few hours then check again.
  • Download new updates directly from the apple website.
  • Download Mac combo update from the Apple support
  • Reset NVRAM, restart the Mac, and press Command, Option/Alt, P, and R, and this will reset NVRAM
  • Make sure to take all the back up before Reinstalling Mac.

FAQ for macOS Installation Couldn’t be Completed

1 Why macOS installation couldn’t be completed?

There are several reasons behind this issue users are facing worldwide. One of the main reasons is the insufficient space, Catalina is 8 GB worth of download, and for that users need 20 GB of free space. One of the other reason could Apple’s server down.

2 What to do when macOS installation Cannot be completed?

If you are facing this issue, then try to open Mac in Safe mode and find the issue. Otherwise try Mac Disk Repair and fix the disk for other problems as well. If everything fails, then reinstall macOS.

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3 How do you check if Apple servers are down?

Sometimes when users are facing issues regarding the new updates, it could be because of the apple server down. Visit Apple system status and check if the apple services are running or not.


macOS installation couldn’t be completed as one of the issues every Mac users face once in a while. There are many solutions to this issue of macOS could not be installed on your computer and we have provided a few solutions for that as well. Make sure to take a backup before trying any of these tricks.

Kuldeep Sathwara
Kuldeep Sathwara
Kuldeep is an iOS lover loves to write about the iphones ,iPad, Mac Updates, issues , Fixes and More.

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