Fix macOS 11 Big Sur Updates Issues (The Definite Guide)

By Jenny | Posted to Home > Mac Data Recovery Tips, updated on March 25th, 2021 | User rating:

Summary: This page collects solutions for over 15 macOS 11 Big Sur updates problems, troubleshooting issues like updates failure, data loss, abnormal battery drain, frozen boot screen, etc.

macOS Big Sur Problems

macOS 11 Big Sur (not the expected macOS 10.16) is a terrific update from Catalina, with multiple new features and an overhauled look. Though not as buggy as macOS Catalina, it doesn't necessarily mean Big Sur is flawless. macOS update problems are of great concern for many users still. You can downgrade macOS Big Sur to macOS Catalina or face the issues and solve them.

Fix macOS 11 Big Sur Updates problems

As far as we are concerned, over 15+ upgrade problems are affecting macOS 11 Big Sur.

  • macOS Big Sur Installation Problems:
  • 1. macOS Recovery mode not working
  • 2. Data issues
  • 3. Fail to download macOS Big Sur
  • 4. Can't install macOS 11 on Mac
  • 5. Older Macs incompatible and bricked
  • 6. macOS Big Sur won't boot up
  • 7. macOS Big Sur stuck in a boot loop
  • 8. Mac stuck in Recovery mode
  • macOS Big Sur Performance issues:
  • 9. Bluetooth is not working
  • 10. Network is not working
  • 11. Mac slow & hot after macOS 11 update
  • 12. Shortter battery issues
  • 13. Mouse problems
  • 14. Apps quit unexpectedly in macOS Big Sur
  • 15. Can't use Airdrop in macOS Big Sur
  • 16. External hard drive read-only on Mac

Now, let's check them one by one and dig for a solution.

1. Data issues in macOS 11 update

In latest 10.15 Catalina and macOS 11, Apple splits the startup disk into two separate volumes, System and Data. It makes data backup difficult especially those apps making (and restoring) bootable backups.

Therefore, it's always recommended to back Mac files up before every major macOS update using the built-in Time Machine.

If you upgraded to macOS Big Sur on a Mac that uses a Time Capsule or other network storage device as the backup destination, your existing backups are also upgraded and can be used only on macOS Big Sur. New backups that are created can be used only on macOS Big Sur.

If you are using a third-party software to back up, then you need to wait until it's ready for macOS 11.

How to restore or recover lost files after macOS Big Sur update?

Though Apple has made a precaution that important files might get lost if the macOS update is interrupted, many of us still forget to back up our Mac with the built-in tool Time machine. As a result, private data like photos and documents might have gone once after updating the system.

How to fix:

  1. If you have backed up your Mac to an external hard drive with Time Machine, you can simply restore the Time Machine backups.
  2. How to restore Mac files from Time Machine backup?
  3. If you don't have any backup while the failed macOS Big Sur stops your Mac from booting up, you can try iBoysoft Data Recovery for Mac to get files off Mac that won’t turn on.
  4. How to recover data from Mac that won't turn on?
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2. Fail to download and install macOS Big Sur

macOS 11 fails to download with some messages like "The network connection was lost", "Installation failed", or "there is not enough space".

Can't download macOS Big Sur or take a too long time, what to do?

With a large size of over 12 GB, it might take a while to download macOS 11. However, if downloading the software takes time more than you expect (like hours), some things go wrong. In some cases, messages like 'macOS Big Sur download has failed' might cast a chill over you.

How to fix:

  • Check your Internet connection (either an Ethernet or WiFi) and make sure it's fast and stable enough.
  • Make sure the task of downloading macOS software update is working fine. Or you can restart your Mac and try it again.
  • Make sure you have made enough room for the software on the target disk.
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Why macOS Big Sur Updates Are So Huge & How to Mitigate

macOS Big Sur updates are getting larger, especially on M1 Macs. See what causes the large installer file and how to cut back on the size. Read more >>

Can't install macOS Big Sur on Mac, why?

A successful macOS software update is not as easy as you think. After downloading, if macOS Big Sur won't install on your Mac machine, all your effort might be in vain. Your Mac may freeze on setting up your Mac, and some older MacBook Pro machines even get bricked by macOS Big Sur.

This could be a result of installing into the same APFS container as previous versions of macOS Catalina 10.15. Another possible reason for "macOS Big Sur Cannot Be Installed On This Computer" is that macOS 11 simply is not compatible with your Mac (e.g. iMac 2020, Retina 5K, 27-inch).

How to fix:

  • If you can't upgrade from macOS 10.15 Catalina to Big Sur, you need first update to 10.15.6 before installing macOS Big Sur.
  • If your Mac is T2-secured, to install macOS Big Sur, you need to boot your Mac to macOS Recovery mode > Utilities > Startup Security Utility, and then make sure the Secure Boot option is NOT set to "No Security".
  • If you receive the error "you may not install to this volume because it is currently being encrypted" when selecting a disk to install macOS Big Sur, wait for the disk encryption to finish and then disable File Vault in Safe Mode (Apple menu > System Preferences > Security & Privacy > FileVault) before reinstalling.
  • If you fail to upgrade to macOS 11 Big Sur and receive "an error occurred applying the software update", try to restart with "Command + R" or "Command + Option + R", and then reinstall macOS in macOS Recovery Mode.
  • If you fail to install the macOS software because the Mac goes sleep while preparing macOS Big Sur 11, you can simply adjust Energy Saver settings by Apple menu > System Preferences > Energy Saver and then try it again.

macOS Big Sur bricked some incomaptible Mac models

Another possible reason for "macOS Big Sur Cannot Be Installed On This Computer" is that macOS 11 simply is not compatible with your Mac (e.g. iMac 2020, Retina 5K, 27-inch).

Make sure your Mac is in the list of compatible models. DO NOT install macOS Big Sur if you are using a MacBook Pro earlier than late 2013 and mid 2014. If it has already casued a problem, you need to reinstall macOS or downgrade the macOS to Catalina.

3. Startup issues after installing macOS Big Sur

After installing macOS Big Sur, the Mac will then automatically restart from the newly installed system. What comes along with is a repeated boot loop, restarting, black screen, and then loading macOS 11 Big Sur. But if any problems occur or any part of those gets stuck, the MacBook won't turn on.

You might see it stuck on the loading screen with an Apple logo, or return some symbols that you have never seen on your Mac, such as a flashing globe, a folder with question mark, pink screen of death, or a prohibitory icon. Finally, the macOS update just crashed and bricked your computer.

How to fix:

  • Force your Mac to restart.
  • Repair your Macintosh HD by booting into macOS Recovery mode > Disk Utility > First Aid.
  • Restart your Mac to Safe Mode and reinstall macOS
  • Erase your Macintosh HD and create an external bootable installer.

Related articles:

How to fix Mac stuck on loading screen?

How to fix Mac black screen after macOS Big Sur update?

How to fix when Mac shows a flashing folder with a question mark?

How to fix the prohibitory symbol at Mac startup?

How to fix if Mac won't let you log in with right password?

Mac stuck in a boot loop after macOS update

Mac will restart for several times after macOS Big Sur update, so keep your Mac connecting to the power source during this process.

But if things do not go well after waiting, you can try these solutions:

1. Try to boot into Safe Mode. Some third-party software (Kernel Extension or a LaunchDaemon) installed on your Mac might be causing this issue, which can be isolated by Safe boot.

2. Reinstall macOS.

macOS Recovery Mode is not working in macOS Big Sur

Some experienced users may find that they can't boot into macOS Recovery mode to fix some issues with Command + R.

Then you can try Command + Option + R, or Shift + Option + Command + R.

If it's a Mac with Apple Silicon M1 chip, try to access macOS recovery and security options at startup by the on-screen Startup Manager

In the new system architecture, you can hold down the power button and access the new startup screen for recovery options like macOS reinstall.

Mac stuck in Recovery mode on Apple Silicon MacBook

The recent Apple Silicon MacBook (M1) was built-in with macOS Big Sur 11.0, while it may cause problems if you want to enable some system extensions in macOS Recovery mode for apps. The Mac will get stuck in Recovery mode and keep spinning.

To solve this problem, the only thing you need to do is to update your system to the new major update macOS 11.4 Big Sur.

Then you'll be able to access macOS Recovery mode again.

4. Poor Performance When Using macOS Big Sur

Fortunately, you succeed in downloading, installing, and booting from macOS Big Sur. But the experience in using this system maybe not as good as you expected.

You may experience Mac sound not working, Mac speed slowing down, Mac frozen, or other issues. Read on and check what you can do when suffering from those problems.

How to fix if macOS Big Sur slows, freezes, heats the Mac?

It's one of the most common problems discussed in forums. macOS 11 Big Sur could lag your Mac and gets computers really hot, especially you are using MacBook Air and MacBook Pro that are relatively old. Before you downgrade from macOS Big Sur to Catalina, try the following things.

How to fix:

  • Disable unnecessary login items by Apple menu > System Preferences > Users & Groups > Login Items.
  • Quit processes or applications in Activity Monitor (the Mac Task Manager) if your Mac freezes on the beachball.
  • Quit or disable the Spotlight Search feature when a lack of system resources heats up your Mac.

Bluetooth is not working in macOS Big Sur

Bluetooth makes it easier when you work on your Mac with wireless devices in-between. So if the bluetooth is not available after macOS 11 update, try to:

For Bluetooth issues in macOS Big Sur, you can press Shift + Option and click the Bluetooth icon in the menu bar > Reset the Bluetooth module > OK > restart the Mac.

Network (WiFi) is not working in macOS Big Sur

The importance of the Network like WiFi connection goes without saying. Either of them could be not functional after upgrading to macOS 11.

For Network issues, you can go to System Preferences > Network > Wi-Fi > Advanced > Remove the connected WiFi connections > restart Mac and reconnect to the Network.

How to fix abnormal battery drain in macOS Big Sur?

For notebooks like MacBook Air and MacBook Pro, battery drain could be a hassle. However, macOS Big Sur could make your battery reach its low point faster than before, or in an abnormal way due to the running background wor.

MacBook Pro not charging, what to do?

How to fix:

Mouse problems in macOS Big Sur

If you've installed macOS Big Sur and found your Apple Mouse not working, open up the ~/Library/Preferences/ directory in finder and select and delete the following plist files and restart your Mac to get the mouse working:


5. Built-in or Third-party Apps Issues in macOS Big Sur

Software is one of the most critical parts using any computer, which includes built-in programs and third-party apps. In the new macOS Big Sur, software incompatibility could cause apps unexpectedly quit, kernel panic, or even the whole system crash.

Apple Menu bar disappeared in macOS 11 Big Sur, how to fix?

Strange but true, some users report that the Mac menu bar is missing icons such as the Clock, WiFi, Control Center, etc. This is reasonable as any new operating system could be glitchy. In this case, you can simply restart your Mac or follow these steps:

  1. Step 1: Open System Preferences > Users & Groups.
  2. Step 2: Click on Login Options and type your admin password.
  3. Step 3: Disable the option "Show fast user switching menu as".
  4. Step 4: Once the menu bar is back, go to System Preferences once again and select Dock & Menu Bar (the new preference pane that lets you show/hide controls).
  5. Step 5: Disable Fast User Switching to remove it from Control Center.

External hard drve is read-only in macOS Big Sur

This is a long standing issue in macOS, not only in macOS Big Sur. That external hard drive is read only after plugging in to the Mac machine, which generally is caused by the Windows NTFS file system. So, if you can't write to your disks, check those things:

If it is other file system, read our article as below to fix it:

How to solve external hard drive read-only on Mac?

Can't use Airdrop in macOS Big Sur, how to fix?

You might be unable to use AirDrop on a Mac running macOS 11 for files transferring and sharing. This could result from System Integrity Protection (SIP), which is a bug for macOS Big Sur beta. You can simply go to disable SIP.

How to fix AirDrop not working?

There are many other software issues like software unexpectedly quit, and apps like VirtualBox, AdGuard, Chrome, and Steam for Mac won't response in macOS Big Sur. What we can advise is to downgrade to a previous system like macOS Catalina and Mojave, and do not upgrade to macOS Big Sur until it is in a stable condition.

Or you can factory reset the Mac to return to the defaults for a completely clean macOS Reinstallation to get rid of the issues.


No one can guarantee that updating to macOS Big Sur is 100% safe, especially in the buggy stage that bursts out problems like:

But what you can do is to back up your Mac files and get noticed possible problems. Then, when you want to upgrade to macOS Big Sur, you won't risk data loss and you are prepared for known issues and data recovery.

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I turned off the file encryption, other wise at start up one has to put in the pass word twice.• Once to start the login• Once to decrypt the the files so one can use the computer.It seems the Big Sur 11.4 starts up much better when at shutting down-you check the box thatsays open windows at start up even when none are open.

2021-06-23 16:40:28


An error occurred while downloading the selected updates. Please check your internet connection and try again. My internet connection is fine. Why am I getting this error when I try to update Mac OS Big Sur 11.3.1... Even before this upgrade my iMac 27 (late 2015) with 48Gb of memory and i5 Core running 3.3 GH, it keeps freezing up and often restarting when I am in the middle of doing something causing me to lose my work. Frustrating!!!

2021-05-06 14:41:58

Vivian reply to Vince:

Hi Vince! You can try the way below to fix the Download Failed error:1.Reboot your Mac into macOS Recovery2.Setting Startup Security to high 3.Restart your Mac and do the update again4.If you still run into the same error, try to do the installation in Safe ModeMake sure that the internet connection is certainly good enough and download speed is great. If you still have any questions, send details to [email protected] to get more help.

2021-05-06 19:39:42

Maria Lewis

Apple Music automatically opens and starts playing whenever I connect my Bluetooth headphones and turn them on. How to stop this from happening?

2021-04-11 18:10:58

Vivian reply to Maria Lewis:

Hi Maria! Here is a way can help you: 1. In Apple Music go to "Preferences..." and "Restrictions".2. Click all the checkboxes under "Disable" including one for "Apple Music". 3. Click the lock to prevent further changes. 4. Click "OK". But this will prevent you from using Apple Music completely. When you want to use Apple Music again, you need to enable it again.

2021-04-11 20:36:56