Apple Fixes a macOS Large Sur Installer Bug That Might Lead to Information Loss

A revised Big Sur update now checks that there is enough free space before starting the installation.

macOS Big Sur appears on a MacBook

Apple fixed a critical bug in the macOS Big Sur installer that would give an error message when trying to update a Mac that did not have the required available space.

A revised update for macOS Big Sur 11.2.1, now available on the Mac App Store, is properly verifying that you have enough free space before starting the installation, Macintosh said on Twitter.

MacOS Big Sur requires 35 gigabytes of free space on your computer's startup disk, excluding the 13 gigabyte installer.

This couldn't have come sooner as one of the consequences of the broken installer is potential data loss. For people who are not in the habit of regularly backing up their Mac with Time Machine, this fairly basic error could potentially have dire consequences.

Mac connected to external backup drive

How to install the new update

The new update is available from System settings> Software update on your Mac. If updates are available, clicking the Update Now button will install them. You may be asked for your administrator password.

The update will not appear if the revised version of macOS Big Sur 11.2.1 is already installed on your computer. The revised installation program has the build number "20D75". Click the Apple menu and select the "About This Mac" option to view the build number of the macOS Big Sur software installed on your Mac.

Related: How to Update to macOS Big Sur

With the About This Mac window open, click the Summary tab. You will see the name of the macOS operating system software on your computer, followed by the version number. To see the build number as well, just click the version number.

You can find out which MacOS version is the latest from a support document on the Apple website.

Big Sur & # 39; s Broken Free Space Check

The problem recently came to light thanks to Mr. Macintosh who originally reported the problem. The release stated that the Big Sur update downloaded without any problems but refused to start because "there was an error preparing the software update".

The problem was attributed to a bug when Big Sur was checking for free space. According to Macintosh, people have been complaining about this since the first public version of macOS Big Sur came out in November 2020. After the release made Apple aware of the problem, the company acted quickly to fix the nasty bug.

"The upgrade will start even if you only have 1% of the free space left and it fails," explains the post. And when the boot drive is nearly 100 percent full, the installer gets stuck in an endless boot loop trying to complete the installation process.

"This will prevent you from accessing your data," warned Macintosh.

The only way to fix this was to delete the macOS software and reinstall it. With the revamped update, now available on the Mac App Store, Mac owners can get on with their everyday lives without worrying about whether an update to Big Sur might clean their startup disk.

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About the author

Christian Zibreg
(72 articles published)

Writing words that support message cycles around the world. I help keep Apple blogs going and keep the internet safe. No mouse buttons were damaged while writing.

By Christian Zibreg

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