Apple’s next MacOS update, called Big Sur, finally moves away from version 10 after nearly 20 years. MacOS 11 is understandably one of the biggest updates yet, boasting a visual overhaul, new notifications, a faster Safari experience, and an upgraded Messages app. It also begins Apple’s transition away from Intel CPUs.
Sound exciting? Then you’re probably anxious for a download. However, it’s currently in public beta, meaning you shouldn’t install it if you’re not willing to take risks. Given its possible instability, this release is better suited for a Mac you don’t primarily use, such as a spare MacBook.
Read on to find out how to download MacOS Big Sur if you just can’t wait for the official, stable release this fall.
Step 1: Check your Mac’s compatibility
This should be your first priority. As with all MacOS updates, some Macs can’t support the new software due to outdated hardware. You certainly don’t want to go through the process of acquiring the public beta if you can’t even run it on your Mac!
Here is Apple’s official list of compatible devices:
- MacBook — 2015 and later.
- MacBook Air — 2013 and later.
- MacBook Pro — Late 2013 and later.
- Mac mini — 2014 and later.
- iMac — 2014 and later.
- iMac Pro — 2017 and later (all models).
- Mac Pro — 2013 and later.
If you’re good to go, then move on to the next step. If not, time to buy a new Mac!
Step 2: Back up your Mac
By nature, betas are unstable. There’s a chance of serious bugs corrupting your data, and you need to be prepared in case that happens. Unfortunately, you can’t merely roll back to a stable version without a complete factory reset. Instead, you should have a Time Machine backup locked and loaded before installing any beta.
That said, creating a backup should be your next priority. The Big Sur beta installer will eventually prompt you to create a backup anyway, so go ahead and do it now if an updated backup isn’t currently available.
When you connect an external drive, MacOS may ask to use it for Time Machine backups. Select Encrypt Backups on the prompt, click the Use Disk button, and you’re good to go. If not, you can manually enable an external disk to use Time Machine by using the following steps.
Step 1: Select Time Machine in System Preferences.
Step 2: Click the Select Backup Disk, Select Disk, or Add or Remove Backup Disk button.
Step 3: Select the external drive in the following window.
Step 4: Click the box next to Encrypt Backups.
Step 5: Click the Use Disk button.
There is another option if you don’t have an external drive and still want to try the beta. You can partition your Mac’s drive and silo off a space to experiment with Big Sur. This is a little more complicated, and you need enough local storage to manage two operating systems. If you are interested, we have a guide where you can learn more.
Step 3: Download the Beta Access Utility
With a backup now in place, you can move to the next step by visiting the Apple Beta Software Program page. Either sign up using a valid Apple ID or sign in if you’re currently enrolled. Unlike the Developers program, access to this public-facing program and its beta software is completely free.
Once you’re signed in and ready to move on, the next step is to enroll your Mac in Apple’s program by downloading and installing the MacOS Public Beta Access Utility.
Go to Apple’s enrollment webpage and click the blue button, shown above, to download the utility to your Mac. You’ll need to choose Allow when prompted to download the file from Apple.
After that, open Finder, navigate to the Downloads folder, and double-click on the MacOSPublicBetaAccessUtility.dmg file.
Step 4: Install Big Sur
With the initial downloaded file now open, you’ll see the MacOSPublicAccessUtility.pkg file contained within. Double-click on that file, and follow the prompts to agree with Apple’s terms and install the required Big Sur profile and installer.
Next, the System Preferences window should open to the Software Update section and show that the Big Sur beta is ready to download. Click the Upgrade Now button to continue.
Your Mac will eventually reboot and initiate the installer. If not, you can locate it within the Applications folder in Finder. Again, you’ll proceed through several prompts: Back up your Mac, agree to Apple’s terms, and select the target drive.
Note that if your Mac has a small drive, like on a MacBook Air, the installer may refuse to upgrade MacOS on that drive, even though MacOS says there’s enough space. This is likely due to Time Machine, which stores local snapshots that the user can’t see — the installer counts against the total storage space.
Step 1: Open Time Machine in System Preferences.
Step 2: Deselect Back Up Automatically (or click the On/Off switch).
Wait a few minutes, and then turn Time Machine back on — this should delete the local snapshots. If not, you’ll need to manually delete these hidden files. Here’s how:
Step 1: Open Terminal.
Step 2: Type: tmutil listlocalsnapshots /
You should see a list of local backups reading something like “com.apple.TimeMachine.2020-08-19-103644.” The MacBook Air we have on hand lists seven of these files, each with a different number after the August 19 date.
Step 3: Type the following, and replace the date and number with whatever you see on your Mac: sudo tmutil deletelocalsnapshots 2020-08-19-103644
Another way to bypass storage issues is to move the Install MacOS Big Sur Beta app to an external drive. The update downloads to the external drive as well — just select the target drive during the initial installation process.
Finally, click Install to finish and wait for your Mac to reboot or manually click the Restart button.
This update could take some time, but be sure to check on it regularly to see if Apple needs you to make any decisions. When it’s finished, your Mac should boot into the Big Sur beta. Again, you may run into issues given this is beta software, so be wary.
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