Fix Big Sur Update Issues(Can't Install on Macintosh HD)

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 Big Sur problems are still of great concern for many users. You can downgrade macOS Big Sur to macOS Catalina or face the issues and solve them.

As far as we are concerned, except for Mac not recognizing external monitor, Macs keep crashing, and Touch ID not working on Mac after the update, there are 15+ problems with Big Sur.

What do you think about this list? Share your opinion on social media!

In the following sections, we will talk about practical solutions to fix macOS Big Sur problems. Let's get started.

Data issues in macOS 11 software update

Since macOS 10.15 Catalina, Apple split the startup disk into two separate volumes, Macintosh HD and Macintosh HD - Data. It makes data backup with third-party apps difficult, especially those that offer bootable backups.

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

Suppose you upgraded to macOS Big Sur on a Mac that uses a Time Capsule or other network storage device as the backup destination. In that case, your existing backups are also upgraded to be used on macOS Big Sur. Note that these backups and new backups created after are only compatible with Mac computers running Big Sur and later.

If you are using third-party software to back up your Mac, check if it's ready for macOS 11.

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

Though Apple has taken a precaution that important files may get lost if the macOS software update is interrupted, many of you still forgot to back up your MacBook Air/MacBook Pro/iMac/Mac mini. Here is what you should do if you've encountered data loss after the macOS software update:

How to fix:

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

Fail to download and install macOS Big Sur

While downloading and installing macOS 11, users have experienced failures along with various error messages, such as:

Can't download macOS Big Sur or the process takes too long, what to do?

With a large size of over 12 GB, it might take a while to download macOS Big Sur. However, if the macOS download takes more time than expected (like hours), there's likely insufficient storage space or an unstable internet connection. You can read below for the solutions to the "macOS Big Sur download has failed" error.

Fix macOS Big Sur not downloading:

macOS Big Sur cannot be installed on Macintosh HD?

Sometimes, smooth downloading doesn't guarantee a perfect installation, as you may get stuck on "Setting Up Your Mac." In this case, you will likely receive an error notification saying, "macOS Big Sur cannot be installed on Macintosh HD." or "the update cannot be installed on this computer." on Big Sur. There are a few reasons for that:

Why can't Big Sur be installed on Macintosh HD?

You may also see a similar message reading "macOS Big Sur Cannot Be Installed On This Computer" when you attempt to install Big Sur on an unsupported Mac. (e.g. iMac 2020, Retina 5K, 27-inch).

To ensure a successful macOS installation, you need to check whether your Mac is supported before downloading macOS Big Sur. Here is the list of Mac models supporting macOS Big Sur:

• MacBook Pro (Late 2013 and later)
• MacBook Air (Mid 2013 and later)
• MacBook (Early 2015 and later)
• iMac Pro (2017 and later)
• iMac (Mid 2014 and later)
• Mac Mini (Late 2014 and later)
• Mac Pro (Late 2013 and later)

Suppose you can't install the downloaded macOS Big Sur update even with a compatible Mac model, delete inessential files to make more free space for it (Check how much disk space you have in Storage Management), then follow the solutions below.

Fix macOS Big Sur not installing:

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Startup issues after installing macOS Big Sur

After installing macOS Big Sur, the Mac will automatically restart from the newly installed system. What comes along with is a repeated boot loop, restarting, a 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 MacBook Air/MacBook Pro, such as a flashing globe, a folder with a question mark, the pink screen of death, or a prohibitory icon.

Here are the solutions to use when you're having trouble logging into your Mac after installing macOS Big Sur.

Fix macOS Big Sur startup issues:

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?

macOS Big Sur upgrade bricked some incompatible Mac models

If you manage to perform a Big Sur installation on an incompatible Mac, especially on an old Mac model, chances are, it won't run smoothly. Even worse, it may brick your Mac, as many users testified. You can save your Mac by downgrading Big Sur to Catalina if that happens.

Mac stuck in a boot loop after macOS update

While Mac repeatedly restarts after the Big Sur installation, you should keep your Mac plugged in to avoid failures. But if you are stuck in a loop where you log in and get logged out again, try these solutions:

Fix 1: Remove the file that makes macOS think it's starting Big Sur for the first time. (It's safe to delete this file because it won't affect other data.)

Fix 2: Boot Mac into Safe Mode to isolate problems caused by third-party software (Kernel Extension or a LaunchDaemon) that launches when Mac boots. If you can log in successfully in Safe Mode, remove all log-in items and re-add them to find the culprit. If your Mac Safe Mode is not working, try the next fix.

Fix 3: Reinstall macOS.

Big Sur Recovery mode not working

After the Big Sur installation, some users may fail to boot into Mac Recovery with the Command + R keys, especially with Macs using Apple Silicon M1 chips. The truth is that M1 Mac has a different way to enter Recovery: Turn off Mac > press the power button until you see the startup options window > choose Options > Continue.

If you are using an Intel Mac but the Big Sur Recovery mode is not working issue exists despite doing everything correctly. It could be caused by a faulty keyboard or, less commonly, a corrupted/deleted recovery partition.

How to fix the Big Sur Recovery mode not working?

Mac stuck in Recovery mode on Apple Silicon Macs

Some may find their Apple Silicon MacBook (M1) with built-in macOS Big Sur more prone to be stuck in Recovery mode and keep spinning when enabling system extensions for apps.

To solve this problem, the only thing you need to do is update your system to the latest available operating system.

Then you'll be able to reaccess Mac Recovery.

macOS Big Sur font issues

You will likely find the Mac fonts not displaying correctly after updating to Big Sur, especially if you use font managers like Suitcase Fusion or have installed personal fonts. In this case, you will see question marks inside boxes when browsing websites in Safari, Google Chrome, Outlook, etc, viewing documents, or reading messages in the Mail app. Some may also encounter the issue that certain fonts won't activate using the auto-activation plugins.

These macOS Big Sur font issues are mainly caused by the conflict that happens when the font from your font manager or your personal font and the fonts included with macOS Big Sur try to activate simultaneously. Fortunately, you can follow the solutions below to fix the problem.

Deactivate Helvetica and Arial fonts in third-party font managers like Suitcase Fusion

If a Helvetica or Arial Regular font exists in both your system font library and the font manager e.g Suitcase Fusion, they will try to activate when the font is requested. This will confuse the app that is asking for the font. Consequently, it shows you the question marks. 

In Suitcase Fusion, you can deactivate the duplicate Helvetica or Arial fonts by selecting it, and clicking the grey activation button. Suppose you are still getting emails with question marks; then you can move on to the next fix.

Deactivate all fonts in your font manager

Another solution to fix macOS Big Sur font problems is to deactivate all fonts in your font manager. This way, you can prevent it from causing any conflicts with the system font library. If the issue still persists, you need to clear the font cache on Mac Big Sur.

Clear font caches on macOS Big Sur

If you are using Suitcase Fusion, you can reset the system font cache and caches created when using Adobe Creative Cloud and Microsoft Office with the steps below:

Alternatively, you can run the command below in Terminal and then restart your Mac to clear font caches on macOS Big Sur.sudo atsutil databases -remove

Restore standard fonts in the Font Book

If you are not employing a third-party font manager, it's likely that the Big Sur update has caused some font files missing. To get back the absent font files, you need to restore standard fonts in the built-in Font Book.

Change the default encoding to Unicode (UTF-8)

Users who have the same Safari browser font problem have managed to get rid of the question marks by modifying the default encoding. If that also happens to you, follow these steps to fix Mac fonts not displaying correctly:

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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 operating system may not be 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, and heats the Mac?

macOS 11 Big Sur could lag your Mac and make computers really hot, especially if you are using MacBook Air and MacBook Pro which are relatively old. Before you downgrade from macOS Big Sur to Catalina, try the following things.

Fix macOS Big Sur freezing/heating/slowing down Mac:

Bluetooth is not working in macOS Big Sur

Bluetooth makes it easier to transfer files between Mac and other devices. If your Mac's Bluetooth is not working after macOS 11 update, try these fixes:

Fix 1: Press Shift + Option and click the Bluetooth icon in the menu bar > Reset the Bluetooth module > OK > Restart the Mac.

Fix 2: Navigate to Finder > Go > Go to Folder > enter /Library/Preferences > press Enter > locate a file called com.apple.Bluetooth.plist > delete it or move it to another folder > restart your Mac and re-connect Bluetooth devices.

Network (WiFi) is not working in macOS Big Sur

If you find your Mac connected to Wi-Fi but no internet or having other issues with internet connection via Wi-Fi or Ethernet after upgrading to macOS Big Sur, here is how to fix the internet connection problems:

Fix 1: Go to System Preferences > Network > Wi-Fi > Advanced > Remove the connected WiFi connections > restart Mac and reconnect to the Network.

Fix 2: Start Mac in Safe Mode and see if you can connect to the internet.

How to fix abnormal battery drain in macOS Big Sur?

You may feel your Mac's battery lasting much shorter right after the Big Sur install. This is likely due to macOS Big Sur doing some background work to set itself up, and the battery life should go back to normal after things are settled down(it usually takes a few hours or a day).

Again, this abnormal battery drain on notebooks like MacBook Air and MacBook Pro could result from underperforming batteries.

Fix macOS Big Sur abnormal battery drain:

            • MacBook Pro not charging, what to do?

Mouse problems in macOS Big Sur install

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

If your mouse cursor disappears on Mac, read this comprehensive guide to fix it: Mouse Cursor Disappears on Mac: Why & How to Fix

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

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

The external hard drive is read-only in macOS Big Sur

External hard drive read-only in macOS Big Sur is usually caused by file permission set to be read-only or file system incompatibility, mostly with NTFS-formatted drives. If you can't write to your disks, check these:

If these quick fixes don't allow you to write to the external disk, read our article 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 file transferring and sharing. This could result from the System Integrity Protection (SIP) bug on the macOS Big Sur beta. You can disable SIP to fix it.

• How to fix AirDrop not working?

There are many other macOS Big Sur problems like software unexpectedly quit, and apps like VirtualBox, AdGuard, Chrome, and Steam for Mac won't respond in macOS Big Sur. If you are unsuccessful with other working solutions, downgrading Big Sur to an older operating system like macOS Catalina and Mojave could do the trick.

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

Verdict

We've covered the common issues you may encounter before, while, and after the Big Sur installation. Here is the summary of macOS Big Sur problems:

Just make sure you have enough disk space for the update and a backup of essential files to avoid data loss if any issues happen.

If you want to install macOS Big Sur on other computers or create a bootable installer, check out this guide: How to Download/Create macOS Big Sur 11.7 ISO File for VirtualBox/VMWare

Hopefully, you have resolved the Big Sur issue by now. Don't forget to share this post with your friends!