A bootable version of the MacOS Catalina installer is one of the frequently translated tools that a Mac user should have at their disposal before upgrading to or performing a clean installation of Catalina. The bootable installer you create in this guide will be located on a USB flash drive, but you can use any bootable device you may have, including internal or external drives.
However, a bootable flash drive is the preferred method; Here's why:
- It is small and easy to store in a safe place.
- It's cheap. You can buy a new USB flash drive that's big enough for this project for under $ 10.
- All current Macs support booting from a USB port. Macs with Thunderbolt 3 can also use a USB flash drive as bootable medium (an adapter may be required).
Why create a bootable macOS Catalina Installer?
There are several reasons to have a bootable macOS Catalina installer. The four main reasons are:
- It allows you to perform a clean installation of your operating system on your Mac using the existing boot drive. Starting up with the installer, you can perform a complete deletion of your normal startup device before installing the new operating system.
- It allows you to install OS on multiple Macs without having to download the installer several times.
- It allows you to archive a copy of the macOS installer, which you may need if you ever want to downgrade to the installer version. You may have noticed that with each new version of macOS released, there are usually some users who have one or more issues with it and want to go back to a previous version. This can usually be done if you have a copy of the installer for the version of Mac OS you want to return to. This bootable installer meets this requirement.
- It can be used as a bootable debugging tool, allowing you to access the same apps found in the Recovery V
What You Need to Create a Bootable MacOS Installer
The list of items needed to complete this project is pretty basic and I suspect you already have everything you need.
A connection to the Internet: You need an Internet connection to download the Apple installer.
A USB flash drive: 8 GB is the smallest size required, at least for all versions of macOS through macOS Catalina. Future versions may require larger flash drives, but so far, 8 GB is large enough. Going bigger is not a bad idea; You can use the extra space on the flash drive to store apps and tools you might need for troubleshooting purposes.
You should also consider using a fast flash drive. A USB 3 flash drive with fast read speeds would be a good choice.
A copy of the macOS Catalina installer. This is usually downloaded via the software update pane (macOS Mojave and later), or the Mac App Store (macOS High Sierra and earlier). If you're working on the beta version of the OS, you can find the downloadable version either on the Apple Developer site or on the Apple public beta site.
About 30 minutes of your time: will take is difficult to estimate; Creating the bootable flash drive depends on the speed of the flash drive you are using and whether you include the time it will take to download the installer, which depends on your Internet connection speed and the amount of traffic that exists when you download. Then take my 30-minute estimate with a grain of salt.
Create bootable macOS Catalina Installer
With everything acquired, let's start by creating the bootable installer. Here are some tips:
When you download the installer, it will automatically start and offer to start the installation process on your Mac. Be sure to exit the installer. Do not let it start the installation process.
Prepare the flash drive by deleting the drive and ensuring it is formatted using macOS Extended (Journaled) file system. You can find instructions in the Rocket Yard guide: How to use macOS Sierra Disk Utility to partition, delete drives. Although the wizard was created for macOS Sierra, it should work well enough to delete a USB flash drive.
We will use the terminal app to execute an instruction that Apple includes in the macOS installer. The instruction "
Normally, commands entered into the terminal must be very precise to operate. This means that the command we want to perform will be different for each version of macOS that you want to create a bootable installer. Since there will probably be at least three versions of macOS Catalina (a developer beta, a public beta and a released version), we will use Terminal, along with a drag-and-drop method, to ensure the terminal command is Always correct no matter what version of Catalina you are going to use.
Open a Finder window and navigate to / Applications. Chapter19659017.d.In the application folder you will find the installer for macOS Catalina. It will have a name similar to
Once you have found the installer, right-click it and select Show Package Content from the pop-up menu.
The Finder window changes to display the internal contents of the installer. Open the Content folder and then the Resource folder. Browse the list of items in the Resource folder until you reach the createinstall media.
For now, set this Finder window aside and place it where it is visible on the desktop.
Open another Finder window by selecting File, New Finder Window from the Finder menu.
From the Finder menu, select Go, Go to Folder.
In the sheet that opens enter / Volumes then click the Go button.
You should now have two Finder windows open, one showing the contents of the Resource folder on the macOS installer, and the latest showing the volumes connected to the Mac.
In the list of volumes you will find the USB flash drive you prepared earlier. The name may be Untitled, or it may have a name you gave it when it was deleted. I chose to name my Flash Drive, which made it easy to find. If you are not sure, you can always return to the Disk Utility, delete the USB flash drive again and give it a distinctive name.
With the two Finder windows ready, it's time to open the Terminal app:
Launch Terminal, located at /Applications/Utilities.vud19659017??Terminal opens and displays a command prompt waiting for you to enter a command. Instead of writing a long command string, you build the command by dragging and dropping.
Warning: The Createinstallmedia command will delete all the contents of the flash drive.
Write the following at the terminal. :
Add a space after the word sudo, Do not press the Enter or Return keys.
From the Finder window that displays the contents of the resource folder, drag the createinstallmedia file to the terminal window and release it on the command prompt. This will create a long entry that begins with / Applications / Install macOS Catalina and ends with / createinstallmedia.
Enter the following in Terminal for createinstallmedia;
Make sure you enter a space after the word volume and do not press the Enter or Return keys.
From the Finder window that displays the contents of the Volumes folder, drag the USB flash drive to the Terminal window.
Type the following in Terminal after the USB flash drive name:
The completed terminal command should look like this if you are using Catalina beta:
sudo / Applications / Install macOS Catalina Beta.app/Contents/Resources/createinstallmedia – Volume / Volumes / Install macOS Catalina Beta Downloadload
Or, if you use the release version of Catalina, it will probably look like this:
sudo / Applications / Install macOS Catalina.app/Contents/Resources/createinstallmedia – Volume / Volumes / Install macOS Catalina Download
Note: The volume and – download cartridge entries must be entered as two bars and then the parameter name . Sometimes your blog software converts a double dash to a single long em dash.
You can now press the Enter or Return key.
Terminal asks for your password. This is the administrator password for the Mac. Enter the password and press the Enter or Return key.
You are asked if you want to continue and delete the flash drive; Enter Y at the terminal and then press return or enter.
Your flash drive will be unmounted and the content will be deleted; The process of creating the bootable installer will then begin.
Once completed, Terminal will display:
Install media that is now available on "/ Volumes / Install macOS Catalina"
Your Flash drive is now ready to be used as a bootable MacOS Catalina installer.
If You Are Not There is another option to use Terminal to create a bootable installer. DiskMaker X is an app that can build the bootable installer for you. The current version of DiskMaker X 8.0.3 is designed for use with macOS Mojave. The DiskMaker team usually updates the app after the release version of a new Mac OS is released.
If you need to create a bootable installer for the beta versions of macOS, Terminal is your best choice. If you want a bootable installer for the released version of macOS Catalina, you can use either Terminal, as described above, or DiskMaker X when it's up-to-date.
Using Bootable Catalina Installer
The bootable installer is used as any other bootable device connected to the Mac. Restart your Mac and immediately hold down the Selection key while the Mac boots start.
After a few moments, Mac's startup processing shows all bootable devices connected to the Mac. Use the arrow keys to select the USB flash drive (probably called Install macOS Catalina).
The startup process will continue, and finally the macOS Utilities window will appear.
At this time, you can choose to:
- Recover from Time Machine Backup: If you have a backup of your system, you can select this option to recover from Time Machine.  Install macOS: You can choose to install macOS Catalina.
- Get online help: Browse the Apple Support page for help
- Disk Utility: Use Disk Utility to delete, repair, format, or partition storage devices.
You can also use the Tools menu to access:
- Startup Security Utility
- Network Utility
Using the various macOS utilities is beyond the scope of this guide, but a common option is to use Disk Utility to delete and feed the Mac's internal boot drive, and then use Install macOS to perform a clean installation of macOS Catalina.
Warning: A clean installation will delete everything on the selected boot device.