How to Re-Download macOS Big Sur Installer from macOS Big Sur

Feb 18, 2021 - 9 Comments

redownload macOS Big Sur from macOS Big Sur

Need to re-download a complete macOS Big Sur installer application, from a Mac running macOS Big Sur? If you’ve already installed and updated a Mac to Big Sur, you may find that trying to re-download it from the Mac App Store doesn’t always work, as it sometimes will simply loop you back to System Preferences, or not be available at all.

Not to worry, as it’s easy to download macOS Big Sur from macOS Big Sur by using the command line as we’ll show you.

Re-downloading macOS Big Sur from a macOS Big Sur Mac

The simplest and most reliable way to redownload macOS Big Sur directly from macOS Big Sur is by using the command line. Assuming you’re currently on a Mac running Big Sur (11.0 or later) here is all you need to do:

  1. Open the Terminal application (hit command+Spacebar and type Terminal, then hit return, or launch it directly from Utilities)
  2. Type the following command:
  3. softwareupdate --fetch-full-installer

  4. You’ll see a “Scanning for installer” message soon followed by a percentage indicator of the download, when finished downloading you’ll see “Install finished successfully”
  5. redownloading macOS Big Sur from Big Sur

  6. Open the /Applications folder on the Mac to find the macOS Big Sur installer application

The complete installer appears in the Applications folder, just like it would if you were updating an older macOS version.

Once you have the installer app you can use it to create a boot disk, bootable USB drive, make an ISO, copy it to another Mac, or do whatever else you were planning on doing with it.

Another option is to use a third party tool like MDS to download complete macOS installers, including Big Sur, but if you’re looking for a quick option that doesn’t require any additional apps, the command line is fairly simple.

For what it’s worth, you can also use the use the softwaredate –fetch-full-installer flag to download macOS installers of other versions too, but obviously that’s beyond the scope of this article but you can read about that if interested. You can also get macOS installers from the App Store, but presumably you already tried that with Big Sur and that didn’t work in this situation.

Do you have another method to re-download macOS Big Sur? Let us know in the comments.

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Posted by: Paul Horowitz in Mac OS


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  1. Anatoliy says:

    Scanning for installer” message soon followed by a percentage indicator of the download, when finished downloading you’ll see “Install finished successfully”

    Question: how long should it take?

    I’m waiting for few hours already. But it still 90% only.

  2. PH says:

    Thank you for these instructions! Worked like a charm after spending hours trying to figure out how to download/install Big Sur onto an ssd drive.

  3. JB says:

    Hi, I downloaded it via the terminal command. What I saw in the Applications folder is “Install macOS Big Sur Beta.” When I clicked it on, it does not specify its version but says that it is a beta. Will it be the most recent one?

  4. klaus says:

    unrelated question but, what is the theme used on the screenshot ? how can i make my macos look like this ?

    i’m talking about details like in the toolbar, button icons have a solid white border line around them..

  5. Kurt Look says:

    Finally an installation method that works. I’ve had a heck of a time getting Big Sur installed for exactly the reasons you stated. The command line approach worked the first time. Two more machines to go!

  6. Sebby says:

    I can’t fetch the Catalina installer this way, though. Says the update isn’t found. I had to use a Catalina machine to fetch the Catalina installer. I wish you could download the apps from the MAS as you used to be able to.

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