1. Select the “Install macOS Catalina” (with left/right arrow keys) and hit the “return/enter” key to boot from the USB flash drive. It may take 5-10 minutes to load the installer from the USB flash drive. Sometimes the progress bar may appear to be frozen or the screen will go black for a minute or two.
2. Create Bootable Usb On Macos Catalina; If you want to use your USB stick with an Apple Mac, you will need to restart or power-on the Mac with the USB stick inserted while the Option/alt (⌥) key is pressed. This will launch Apple’s ‘Startup Manager’ which shows bootable devices connected to the machine. Your USB stick should appear as.
3. Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing. Turn on your Mac and continue to hold the power button until you see the startup options window, which shows your bootable volumes. Select the volume containing the bootable installer, then click Continue.
4. How to make a bootable copy of Catalina on USB drive? To make a bootable copy of Catalina on a USB drive, make sure it has at least 12 GB of free memory. Since your USB drive will be formatted in the process, it’s also important to back up the data you store on it. If your USB drive is ready, follow these steps to create a bootable copy of.

Make sure the USB drive is connected to the Mac. Next, click on the Apple logo from the top left and choose Restart. When you hear the startup sound or see the Apple logo, immediately press and hold the Option key. Select the bootable installer as the startup disk, and follow the instructions.

An external drive that you can use as an installer for macOS Catalina is a handy thing to have. If you have multple Macs to upgrade, it’s a lot more efficient to plug in the USB installer drive and run the installer than to log into the App Store, download the 8.09GB OS installer, and then run it.

In this article I’ll go over the different ways you can create a bootable macOS Catalina installation drive. But before I give instructions on how to create the drive, I’ll go over the items you’ll need and how to get them.

Get an external drive and maybe an adapter

The macOS Catalina installer software is over 8GB, so you need a USB external drive that can hold that much data. The drive can be a thumb drive, hard drive, or SSD.

If you have a 2015 or newer MacBook or a 2016 or newer MacBook Pro, you may need Apple’s $19 USB to USB-C adapter. This will allow you to connect a storage device that uses a USB type-A connector. If you don’t have an external drive and you have a USB-C Mac laptop, you could buy the SanDisk Ultra USB Type-C Flash Drive, which has a USB-C connector. You can get model number SDCZ450-016G-G46.

How to create a bootable macOS Catalina installer drive Put the macOS Catalina installer on an external USB thumb drive or hard drive and use it to install the operating system on a Mac. Turn on your Mac and continue to hold the power button until you see the startup options window, which shows your bootable volumes and a gear icon labled Options. Select the volume containing the bootable installer, then click Continue. When the macOS installer opens, follow the onscreen instructions. MacOS Catalina Patcher lets you install macOS Catalina on Mac computers that are no longer officially supported. It can help you create a bootable USB drive that can be used to install macOS Catalina on Mac computers older than mid 2012. Point to your Mac OS.dmg or.iso file by clicking the add button. After that TransMac will create bootable Mac OS USB within few minutes. Then you can insert it into your Mac, hold down the option key while turn on and boot your system with this USB. If you’re unable to use Internet Recovery Mode or create a bootable USB installer, you can still use a Mac OS X installation disc. These discs are available for OS X Snow Leopard, OS X Lion, and OS X Mountain Lion. If your Mac is from 2012 or earlier, there was an installation disc in the original box.

When creating the boot drive, the storage device is reformatted, so there’s no need to format the drive beforehand.

Get the macOS Catalina installer software

The macOS Catalina installer is available in the App Store. If you launch the App Store app, do a search for “Catalina.” Or, if you click this Catalina App Store link, it will take you to the Catalina App Store webpage, then click on the “View in the Mac App Store” button.

You can read the information to learn more about Catalina. When you’re ready to download the software, click the Download button. (If you’ve already downloaded the installer, the button will say Install instead of Get.)

Once the download is complete, the installer will launch automatically. But don’t continue with the installation. Instead, press Command-Q on your keyboard to quit the installer.

The Catalina installer app will be in your Applications folder, so you can go there and launch it later to upgrade your Mac to the new operating system.

Make a bootable installer drive: The quick way

I used a free app called Install Disk Creator to make the installation drive. Download Install Disk Creator by clicking on the link. When the download is done, you can move it over to your Applications folder. Then follow these steps to create your bootable macOS Catalina drive.

1. Connect your drive to your Mac.

2. Launch Install Disk Creator.

3. In the main window, you’ll see a pop-up menu under Select the volume to become the installer. Click on the menu and select your drive.

4. Under the pop-up menu, you’ll see Select the OS X installer. (macOS used to be called OS X.) If you have only the Catalina installer on your Mac, Install Disk Creator will automatically select it. If you have other macOS installers, you need to click on Select the OS X installer and select the Catalina installer.

5. When you’re ready, click Create installer. Your Mac may tell you that Install Disk Creator wants to make changes, and you need to enter your user name and password. After you do this, the app will take a few minutes to create the boot drive. A progress bar. appears at the bottom of the Install Disk Create window.

If you try to start the process and you get a failure message saying that the drive couldn’t be unmounted, try reformatting the drive first as ExFAT using Disk Utility. Then start the process over again.

Create Bootable Usb Mac Catalina

When the app is done, the installer is ready to use.

I purchased a used 2018 Mac mini desktop and wanted to put a fresh installation of the latest macOS 10.15 Catalina on it. Below are the steps I took.

Note: The instructions below are the same for macOS 10.13 High Sierra and macOS 10.14 Mojave.

Download macOS Catalina

You will need a Mac to download macOS Catalina; you can download Catalina from The Mac Go. (The Mac mini came with macOS 10.14 Mojave so I used it to download Catalina.)

Go to the Mac App Store, search for “macOS Catalina”, and download it. It will be saved to the “/Applications/Install macOS Catalina” location. If the installer automatically launches, just close it.

Note: If you plan to run the installer first to update your current macOS version to Catalina, you will want to move the “Install macOS Catalina” application out of the “/Applications” directory; otherwise, the installer will delete itself from the “/Applications” directory when the upgrade completes. For example, you can move the “Install macOS Catalina” application to the “~/Downloads” directory and run it from there.

Format USB Flash Drive

Because macOS Catalina is 8.4GB in size, you will need a 16GB USB flash drive. You don’t need to delete the existing content on the drive because we will blow it all away in a subsequent step.

If the USB flash drive is not already formatted as “Mac OS Extended (Journaled)”, format it like so:

1. Plug the USB flash drive into your Mac.
2. Launch the “Disk Utility” application.
3. On the left-hand pane, select the USB drive (not the partition under it, if any).
4. Click on the “Erase” tab (or button at the top).
   1. Input a name like “Catalina” (this name will be overwritten later).
   2. Select “Mac OS Extended (Journaled)” for “Format”.
   3. If available, select “Master Boot Record” for “Scheme”.
   4. Click the “Erase” button at the bottom. Click the “Erase” button in the warning popup dialog if you get one.
5. The format operation may take several minutes to complete. (USB 2.0 and large capacity drives may take longer.) After the format completes, the partition will be mounted under “/Volumes/Catalina” (or whatever name you selected above).
6. Close the “Disk Utility” application.

Write macOS Catalina to USB Flash Drive

To create a bootable USB macOS Catalina installer, run the “Terminal” application and this command:

Note: If the createinstallmedia command returns a “Failed to start erase of disk due to error (-9999, 0)” error, then your current Mac OS X version does not fully support the createinstallmedia tool. Use a more recent macOS version (at least Mac OS X 10.11 El Capitan) or manually create the USB installation drive using instructions from Bootable USB Flash Drive to Install Mac OS X 10.10 Yosemite.

The “createinstallmedia” program will erase the USB flash drive, create a new partition named “Install macOS Catalina”, and copy the installation files to that partition. The output will look like:

The above process took 20-30 minutes using my Kingston USB 2.0 flash drive.

Boot From USB Flash Drive

Note: Apple’s How to create a bootable installer for macOS page suggest using the “Startup Disk” configuration (under “System Preferences”) to select the USB flash drive as the startup drive. Then on restart, the Mac should boot from the USB flash drive. Unfortunately, the “Startup Disk” did not list my USB flash drive as a startup option, so I was not able to use this method.

To boot a Mac with the USB flash drive:

1. Insert the USB flash drive.
2. While holding the “option” key down, turn on the Mac to display the Startup Manager.
3. You should see one or more icons, one of which should be called “Install macOS Catalina” for the USB flash drive. (The internal hard drive may not be visible if it does not have a valid, bootable partition installed.)
   • Note: If you don’t see the USB flash drive’s “Install macOS Catalina”, try removing and re-inserting the USB flash drive while viewing the Startup Manager screen. The USB flash drive should then appear after a few seconds.
4. Select the “Install macOS Catalina” (with left/right arrow keys) and hit the “return/enter” key to boot from the USB flash drive.

It may take 5-10 minutes to load the installer from the USB flash drive. Sometimes the progress bar may appear to be frozen or the screen will go black for a minute or two. Be patient.

External Startup Disk Not Allowed

On a newer Mac with the T2 security chip, booting from an external drive may be disallowed by default. Attempting to boot from a USB flash drive will result in a “Security settings do not allow this Mac to use an external startup disk” warning message.

To allow booting from the USB flash drive, do the following:

Mac Catalina Usb Boot Disk

1. Hold down “Command-R” (hold down both the “Command ⌘” and “R” keys) when you start the Mac to launch macOS Recovery. You can release the keys when you see the Apple logo.
   • Tip: An easier alternative is to hold the “Option/Alt” key on boot to launch the Startup Manager. Then just click and release “Command-R” keys to launch macOS Recovery.
2. The macOS Recovery screen contains a top-level “macOS Utilities” menu.
3. Click on the “Utilities” menu and select “Startup Security Utility”. Input your administrator password when prompted.
4. In the Startup Security Utility, under “Allowed Boot Media”, select the “Allow booting from external or removable media” option.
5. If the Mac won’t have access to the Internet (either by wire or wirelessly) when installing macOS Catalina, make sure to select either the “Medium Security” or “No Security” option under the “Secure Boot” section. (You can change the option back to the default “Full Security” afterwards.)
6. Quit the macOS Utilities to restart the Mac.
7. On restart, follow the directions in the previous section to boot from the USB flash drive.

Erase the Internal Hard Drive

When the installer finishes loading, you will see a “macOS Utilities” screen appear. It looks the same as the “macOS Recovery” screen with one difference. In the “macOS Utilities” window, the second option will say “Install macOS” instead of “Reinstall macOS”. In “macOS Recovery”, the “Reinstall macOS” option would just re-install the same version of macOS. The “Install macoS” option will install the macOS Catalina version on the USB flash drive.

Before installing macOS, I wanted a clean slate so I erased the internal hard drive like so:

1. Select the “Disk Utility” option and click the “Continue” button on the bottom to launch the “Disk Utility” application.
2. On the left-hand pane, select the internal hard drive (not the partition under it, if any).
3. Click on the “Erase” button at the top.
   1. Keep the default “Macintosh HD” name or input a new one.
   2. Select “APFS” for “Format”.
   3. Click the “Erase” button at the bottom. The SSD (Solid State Drive) format took less than a minute to complete.
4. Close the “Disk Utility” application.

Install macOS Catalina

Warning: If your Mac has a T2 security chip and you left the “Full Security” option configured in the Startup Security Utility, make sure that Internet access (wired or wireless) is available before starting the macOS Catalina installation. You can configure the wireless network by clicking on the wireless icon at the top-right corner of the macOS Utilities screen.

Back at the “macOS Utilities” window, do the following to start the macOS Catalina installation:

1. Click on the “Install macOS” option and click the “Continue” button.
2. The “macOS Catalina” installer’s splash screen will appear. Click the “Continue” button.
3. Click on the “Agree” button to agree to the license. A popup confirmation window will appear; click on the popup’s “Agree” button.
4. Select the internal hard drive and click the “Install” button.

My Mac mini took 20-30 minutes to complete the macOS Catalina installation. I think there were a couple of reboots in-between. And a few times, the screen would go black for a minute or two. Be patient and give the process an hour or more to complete.

Mac Catalina Bootable Usb

If you run into problems installing macOS Catalina, check the “What Does Giving Up Mean?” section (at the bottom) of Install macOS Sierra Using Bootable USB Flash Drive for possible solutions.

Note: macOS Catalina seems to have an issue with my Dell 24in U2410 monitor. During the initial bootup screen, the monitor shows a blank screen with a message, “The current input timing is not supported by the monitor display”. Thankfully, the monitor works correctly after the bootup completes. And later, this warning message no longer appeared on bootup.

Macos Catalina Bootable Usb Windows

Enjoy your fresh installation of macOS 10.15 Catalina.