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

By Vivian | Posted to Mac Data Recovery Tips on September 5th, 2020 |

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

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.

As far as we are concerned, there are 4 kinds of problems affecting macOS 11 Big Sur.

  • Data loss and macOS 11 update failure
  • Startup issues after installing macOS Big Sur
  • Poor performance when using macOS Big Sur
  • Built-in or third-party apps issues

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

Fix macOS 11 Big Sur Updates problems

1. Data Loss and macOS 11 Update Failure

How to restore or recover files lost in 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:

  • If you have backed up your Mac to an external hard drive with Time Machine, you can simply restore the Time Machine backups.
  • 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.

Related articles:

How to restore Mac files from Time Machine backup?

How to recover data from Mac that won't turn on?

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.

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

How to fix:

  • Make sure your Mac is in the list of compatible models. If not, you need to reinstall macOS or downgrade the macOS to Catalina.
  • 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 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.

2. Startup issues after installing macOS Big Sur

After installing macOS Big Sur, the Mac will then automatically restart from the newly installed system. But troubles could occur when loading macOS 11, and the Mac fails to 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. Finally, the macOS update just crashed 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

Related articles:

How to fix if Mac stuck on the loading bar screen?

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 stuck on the login screen?

3. 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. Read on and check what you can do when suffer 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 if your Mac freezes on the beachball.
  • Quit or disable the Spotlight Search feature when a lack of system resources heats up your Mac.

How to fix if Bluetooth and Network not available in macOS Big Sur

Bluetooth makes it easier when you work on your Mac with wireless devices in-between. And the importance of the Network like WiFi connection goes without saying. Either of them could be not functional after upgrading to macOS 11.

How to fix:

  • 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.
  • 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.

How to fix:

  • Locate the programs that impact the energy most and get insights on energy saving in Activity Monitor > Energy.
  • Reset SMC and PRAM to better manage power, battery, fans, and other related features.
  • Check for your battery lifespan and charge circle count by Apple menu > About this Mac > System Report > Hardware > Power.

4. 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.

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

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

There are many other software issues like software unexpectedly quit, and apps like VirtualBox, AdGuard, Chrome, and Steam 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 released to the public in a stable condition.


No one can guarantee that updating to macOS Big Sur is 100% safe, especially in the testing stage. 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.