Apple hasn’t shipped operating systems on physical media in a full decade, but there are still good reasons to want a reliable old USB stick for macOS Catalina. Luckily, it's not hard to make one—either with a handy graphical user interface or some light Terminal use. Here's what you need to get started:

• A Mac that you have administrator access to. We've created a USB stick from both Mojave and Catalina, but your experience with other versions may vary.
• A 16GB or larger USB flash drive or a 16GB or larger partition on some other kind of external drive. A USB 3.0 drive will make things significantly faster, but an older USB 2.0 drive will work in a pinch; 8GB drives worked for Mojave and older versions of macOS, but the Catalina installer is just a little too large to fit.
• The macOS 10.15 Catalina installer from the Mac App Store (in High Sierra or older macOS versions) or the Software Update preference pane in Mojave. The installer will delete itself when you install the operating system, but it can be re-downloaded if necessary.
• If you want a GUI, take a look at Ben Slaney's Install Disk Creator from MacDaddy. There are other apps out there that do this, but this one is quick and simple.

If you want to use this USB installer with newer Macs as they are released, you'll want to periodically re-download new Catalina installers and make new install drives. Apple rolls support for newer hardware into new macOS point releases as they come out, so this will help keep your install drive as universal and versatile as possible.

Follow the below steps in order to create a bootable macOS Catalina USB Drive. Format your USB Drive:. Connect your USB drive to the USB port of your computer. Press Command+ Space to launch spotlight, type in ‘Disk Utility,” and press the return to launch the app. How to Format an SD Card on Your Mac; How to erase or reformat a Drive using Disk Utility. Let’s start with a brief explanation of the correct way to reformat or erase drives using your Mac. Feel free to skip this section if you already know how to do it. You may want to erase your drive as a quick way to create space for new files.

There's also one new consideration for newer Macs with Apple's T2 controller chip—as of this writing, that list includes the iMac Pro, the 2018 Mac Mini, the 2018 MacBook Air, and 2018 and 2019 MacBook Pros, though Apple keeps an updated list here. Among this chip's many security features is one that disallows booting from external drives by default. To re-enable this feature, hold down Command-R while your Mac reboots to go into Recovery Mode and use the Startup Security Utility to 'allow booting from external media.' If you're trying to install an older version of macOS, you may also need to go from Full Security to Medium Security to enable booting, but if you're just trying to install the current version of macOS, the Full Security option should be just fine. And if you're just doing an upgrade install rather than a clean install, you can run the Catalina installer from the USB drive from within your current installation of macOS, no advanced tweaking required.

Format Flash Drive Mac Catalina Island

The easy way

Once you've obtained all of the necessary materials, connect the USB drive to your Mac and launch the Install Disk Creator. This app is basically just a GUI wrapper for the terminal command, so it should be possible to make install disks for versions of macOS going all the way back to Lion. In any case, it will work just fine for our purposes.

Install Disk Creator will automatically detect macOS installers on your drive and suggest one for you, displaying its icon along with its path. You can navigate to a different installer if you want, and you can also pick from all the storage devices and volumes currently connected to your Mac through the drop-down menu at the top of the window. Once you're ready to go, click 'Create Installer' and wait. A progress bar across the bottom of the app will tell you how far you have to go, and a pop-up notification will let you know when the process is done. This should only take a few minutes on a USB 3.0 flash drive in a modern Mac, though using USB 2.0 will slow things down.

The only slightly less-easy way

The Install Disk Creator is just a wrapper for the terminal command to create macOS install disks, so if you’re comfortable formatting your USB drive yourself and opening a Terminal window, it’s almost as easy to do it this way. Assuming that you have the macOS Catalina installer in your Applications folder and you have a Mac OS Extended (Journaled)-formatted USB drive (which is to say, HFS+ and notAPFS) named 'Untitled' mounted on the system, you can create a Catalina install drive using the following command.

sudo /Applications/Install macOS Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled

The command will erase the disk and copy the install files over. Give it some time, and your volume will soon be loaded up with not just the macOS installer but also an external recovery partition that may come in handy if your hard drive dies and you're away from an Internet connection. If you would like to create an install drive for a macOS version other than Catalina, just tweak the paths above to refer to Mojave or High Sierra instead.

Whichever method you use, you should be able to boot from your new USB drive either by changing the default Startup Disk in System Preferences or by holding down the Option key at boot and selecting the drive. Once booted, you'll be able to install or upgrade Catalina as you normally would. You can also use Safari, Disk Utility, or Time Machine from the recovery partition to restore backups or troubleshoot.

Disk Utility User Guide

In Disk Utility on Mac, you can erase and reformat storage devices to use with your Mac. Erasing a storage device deletes everything on it.

Format Flash Drive Mac Catalina Installer

1. If you have any files you want to save, copy them to another storage device.

2. Open the Disk Utility app on your Mac using one of the following methods, depending on the type of disk or volume you want to erase:

   • If you want to erase your startup disk: Start up from macOS Recovery, then choose Disk Utility from the Recovery window.

   • If you want to erase any other type of storage device: Double-click Disk Utility in the /Applications/Utilities folder.

3. Choose View > Show All Devices.

4. In the sidebar, select the storage device you want to erase, then click the Erase button .

5. Click the Scheme pop-up menu, then choose GUID Partition Map.

6. Click the Format pop-up menu, then choose a file system format.

7. Enter a name.

8. (Optional) If available, click Security Options, use the slider to choose how many times to write over the erased data, then click OK.

   Secure erase options are available only for some types of storage devices. If the Security Options button is not available, Disk Utility cannot perform a secure erase on the storage device.

9. Click Erase, then click Done.

Note: With a solid-state drive (SSD), secure erase options are not available in Disk Utility. For more security, consider turning on FileVault encryption when you start using your SSD drive.

Mac Os Catalina Flash Player