Why Can't I Update My Mac? Fix It and Update Mac to The Latest macOS Big Sur

Do you know how all the accesses to upgrade macOS including Big Sur or the latest update are not working? We'll list all the possible causes that prevent you from upgrading Mac via Apple software update, macOS installer, or resetting macOS.

Table of Contents

When you can't update Mac, the Apple Software Update doesn't work, or the latest macOS Update Big Sur cannot be installed on your Mac computer, don't worry. On this page, we'll walk you through all the possible causes and present respective fixes to resolve these issues to guide you to update to the latest macOS version successfully. 

Let's start here.

About macOS Update

macOS or Mac OS X is set to automatically check for and download software updates once a week. When there is an available update, the system will pop up a notification message to notify all Mac users.

However, when the Apple Software Update doesn't work on a Mac computer, you may try the listed accesses to download and install the latest macOS update on your computer:

  • Manually download the update.
  • Download a stand-alone update installer from Apple.
  • Reset Mac or re-install the operating system, etc.

Why Can't I Update My Mac?

According to many Mac users, they are not quite clear about why they can't find software updates or why they can't install the downloaded macOS update on Mac. Let's see the possible reasons that block you from installing the latest macOS update:


  • Apple Software Update tool fails
  • Unstable network connection
  • Insufficient storage space for installing the latest macOS update
  • Mac is too old to update
  • Mac doesn't detect or says no new update


It doesn't matter if you know the causes or not. Here is a list of symptoms that you can check with your Mac computer, if you are with one of the symptoms, move to the next part and follow fixes to resolve this issue immediately: 

  • Mac freezes in downloading or installing macOS updates.
  • Mac takes too long to download the new update: Downloading macOS **...
  • Error message 1: The macOS installation couldn't be completed
  • Error message 2: An error occurred while installing the selected updates
  • Error message 3: There is not enough space on the selected volume to update the OS

How to Fix "Can't Update Mac to the Latest macOS Big Sur" Error? All Your Fixes Are Here

Do you know what to do when the Apple software update, macOS installer, or even resetting macOS all don't work on Mac computer? Follow the solutions offered in this part to get rid of the "Can't update Mac" error and install the latest macOS version Big Sur on your computer now.

Method 1. Check Network Connections and Reboot Mac

Applies to Fix: Download taking too long

When your computer is stuck with the "Downloading macOS **..." message, a weak network connection is the main cause of this error. 

How to Fix:

Step 1. Close the macOS downloading window.

Step 2. Disconnect Mac with your WiFi.

Step 3. Shut down and restart your router. 

Restart router

Step 4. Reconnect your Mac and other devices with WiFi.

Make sure that the WiFi connection is working fine on both your Mac computer and other devices.

Step 5. Attempt to run a new software update:

Go to Apple Menu > Choose System Preferences > Click Software Update > Wait for Mac to configure new updates > Click Update Now.

Check for software update on Mac

If the software update doesn't detect a new update, or the software update fails, move to the next fix for help.

Fix 2. Manually Update Mac to The Latest macOS Version

Applies to Fix: Apple Software Update Failed, "The macOS Installation Couldn't Be Completed" error.

macOS installation couldn't complete error

How to Fix:

Step 1. Shut down and restart your Router.

Step 2. Make sure that your Mac computer is connected correctly to WiFi.

Step 3. Shut down Mac and restart Mac.

Step 4. Close all applications on Mac computer.

Step 5. Retry to manually update Mac:

Open the Apple Menu > Open System Preferences > Click Software Update > Let Mac check for new update > Click each update to apply and click Install Update or Install Now.

Manually update Mac

Fix 3. Try Stand-Alone Update (Download Updates from Apple Site)

Applies to Fix: Installation failed - "An error occurred while installing the selected updates. "

macOS installation failed

When Mac cannot detect a new update via Apple Software Update, you can try this fix - download a new update from Apple Site.

How to Fix: 

Step 1. Open the Apple Support Download site: 


Step 2. Select the desired update to install.

Step 3. Download and apply the update.

Download macOS update from apple site

Follow the onscreen guide to install macOS on your Mac computer.

Step 4. Wait for the update to install, once completes, restart Mac.

Fix 4. Clean Mac Disk and Re-download/Re-install macOS Update

Applies to Fix: "There is not enough space on the selected volume to update the OS".

Insufficient space for installing macOS update

How to Fix:

Step 1. Clean Mac disk space by deleting cached files and other big files. 

Note: If you have important big files, saving them to an external hard drive is a wise choice. (10GB is needed.)

When you mistakenly deleted files, reliable Mac file recovery software is here to help. 

Step 2. Continue to check for new updates via Apple Software Update. 

Or click to continue installing the downloaded Mac update.

Step 3. If Software Update fails, go to the Apple download site to download the latest new update.

related articles

How to Update/Reinstall macOS Without Losing Data

This page covers the full process of how to update and install the latest macOS Big Sur, Catalina, Mojave, etc. on Mac without losing any data. Follow through this page to get the desired macOS installed on your computer now.

install macOS

Fix 5. Reset Mac and Check for New Update

Applies to Fix: Mac is too old to update, Update not found - "The requested version of macOS is not available".

macOS update not found

How to Fix:

Step 1. Restart Mac and hold Command + ROption+Command+R, or Shift+Option+Command+R.

Step 2. When the Apple logo appears, release the pressed keys, select Disk Utility in the Recovery Mode.

Open Disk Utility

Step 3. Select Erase > Select the startup disk in Mac and click Erase.

Note that this may erase and remove important files on your Mac. So make sure that you back up all important files in advance. Otherwise, your last option for data recovery is turning to Mac file recovery software as recommended at the end of this page.

Step 4. Select Quit Disk Utility and on the new window, select Install macOS.

Step 5. Follow the onscreen guide to install macOS on your computer.

Step 6. Restart Mac when the installation of macOS completes.

Step 7. Run Software Update to check for new macOS update. Or, go to the Apple Download site to download and install the desired update.

Bonus Tip: Recover Lost Files After macOS Update

When you found previous files or data were missing on Mac after installing a new update, don't worry. You can first go and check if you have the backups.

If yes, congratulations. You can directly restore missing files from the backup. 

If no, stop using your Mac immediately. Then turn to reliable Mac file recovery software like EaseUS Data Recovery Wizard for Mac for help.

EaseUS Data Recovery Wizard for Mac

Step 1. Select the location to scan

Launch EaseUS Data Recovery Wizard for Mac and choose the hard drive, SSD,  SD card, USB flash drive, or TF card where you lost data. Click "Search for lost files" to start scanning.

Note: Before data recovery, you'd better click "Disk Backup" from the left sidebar to create a backup of your Mac to avoid further data loss. After backing up, the software can recover data from the Mac backup, and your computer can wirte new data again.

select a location and click search for lost files

Step 2. Filter lost Mac data

The software will automatically scan for lost data on MacBook/iMac. When the scan completes, filter wanted data through the "Type" and "Path" buttons.

filter lost files in types

Step 3. Recover lost data or files

Double-click a file to preview it. Then, click the "Recover" button to restore the lost data to another place. 

click recover to recover lost data

Can't Update Mac Error Is Fixed, Go & Install the Latest macOS on Your Mac Now

On this page, we explained the causes of why can't I update my Mac issue and the symptoms to help you define the error.

It doesn't matter if you can't download a new update on Mac. Back up all your Mac files to an external hard drive, follow the fixes here one by one. You'll successfully get rid of this issue and install the latest macOS update such as Big Sur, on your computer.

For the lost files, you can either restore them from backup or turn to EaseUS Mac file recovery software for help.

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Updated by Jaden

Jaden is one of the editors of EaseUS who lives and works in Chengdu, China. She focuses on topics concerning PCs and Mac data recovery. Jaden is committed to enhancing professional IT knowledge and writing abilities. She is always keen on new and intelligent products.

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Written by Tracy King

Tracy became a member of the EaseUS content team in 2013. Being a technical writer for over 10 years, she is enthusiastic about sharing tips to assist readers in resolving complex issues in disk management, file transfer, PC & Mac performance optimization, etc., like an expert.

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