# macOS Catalina USB Installer Not Bootable: What to Do

## How to fix if the macOS Catalina USB installer is not bootable?

Quick Answer:

If your**macOS Catalina USB installer is not bootable**, check for any connection issues.

If that's not the case, open Disk Utility, right\-click the bootable volume, select Get Info, and check if "Bootable" is labeled "Yes."

| If it is, it means that the Catalina USB installer is actually bootable. | 1. Go check if your Mac supports macOS Catalina 2. Enter macOS Recovery mode \> Startup Security Utility \> check "Allow booting from external or removable media." \(for a Mac is equipped with a T2 chip\) 3. Ensure the way you boot your Mac from the Catalina USB installer is correct. Reboot your Mac while pressing down the Option key until the bootable volumes appear. |
| --- | --- |
| If it isn't, it means the Catalina USB installer is unbootable. | Use iBoysoft DiskGeeker, which requires a few clicks to create a bootable macOS Catalina USB installer. |

![USB Catalina installer not bootable](https://iboysoft.com/images/en-howto/usb-catalina-installer-not-bootable/summary-usb-catalina-installer-not-bootable.jpg)

You are going to start up your Mac from a macOS Catalina USB bootable installer for[macOS downgrading](https://iboysoft.com/mac-data-recovery/how-to-downgrade-macos.html)or tests, only to find your[Mac won't boot from the USB](https://iboysoft.com/howto/mac-wont-boot-from-usb.html).

Booting a Mac from a USB is not an easy job; it is error\-prone. Here, we list all the checks and fixes for troubleshooting this issue. Follow them carefully, and then you can boot your Mac from the Catalina bootable USB installer successfully.

## Check if the Catalina USB installer is actually unbootable

Your USB installer not showing up at the Startup Manager or Startup Disk settings may not mean it is not bootable.

It can be caused by:

- The faulty connection
- System incompatibility
- Improper settings
- The incorrect way to [boot your Mac from the USB](https://iboysoft.com/mac-data-recovery/mac-boot-from-usb.html)

Consequently, you mistakenly think the**bootable USB installer is not bootable**.

So, to ensure whether your macOS Catalina bootable USB installer is bootable or not, go to Disk Utility and check if it shows up there.

If the macOS Catalina USB installer doesn't appear in Disk Utility, check the connections by:

1. Unplugging the USB.
2. Trying a different USB port.
3. Changing a USB cable.

If it shows up in Disk Utility, check whether the Catalina USB installer is bootable or not:

1. Right\-click the macOS Catalina bootable volume from the left sidebar of Disk Utility.
2. Select "Get Info." ![Catalina bootable volume Get Info](https://iboysoft.com/images/en-howto/usb-catalina-installer-not-bootable/catalina-bootable-volume-get-info.jpg)
3. Find the "Bootable" row and see whether it is labeled "Yes." **"Yes" means the Catalina USB is bootable** . "No" means it is not bootable. ![check if Catalina bootable volume is bootable](https://iboysoft.com/images/en-howto/usb-catalina-installer-not-bootable/check-if-catalina-bootable-volume-is-bootable.jpg)

Share to help others verify if their USB Catalina installer is not bootable.

## Case 1: The Catalina USB installer is bootable, but you can't boot your Mac from it

### ① Check if your Mac supports macOS Catalina

A macOS Catalina bootable USB installer cannot boot all Mac models. Only Mac devices that support macOS Catalina can boot from it.

Here's the checklist of macOS Catalina\-compatible Mac machines:

- MacBook Pro \(2020 \- Mid 2012\)
- MacBook Air \(2020 \- Mid 2012\)
- MacBook \(2017 \- 2015\)
- iMac Pro \(2017\)
- iMac \(2020 \- Late 2012\)
- Mac mini \(2018, Late 2014, Late 2012\)
- Mac Pro \(2019, Late 2013\)

Note:Since the debut of M1 Macs was preinstalled with macOS Big Sur, M1 and other Apple Silicon Macs don't support macOS Catalina and earlier.

If your Mac isn't on the list, you should re\-create a macOS bootable USB installer that is compatible with it.

### ② Modify the startup security settings

A Mac equipped with an Apple T2 secure chip is not allowed to start up from a bootable USB installer by default. Thus, the bootable Catalina USB is not booting.

To check whether your Mac is T2\-secured:

Press and hold the Option key and simultaneously click the Apple menu \> "System Information," then select "Controller" under "Hardware."

![check if your Mac has a T2 chip](https://iboysoft.com/images/en-howto/usb-catalina-installer-not-bootable/check-if-mac-has-t2-chip.jpg)

If it is, you should change the settings in Startup Security Utility to enable your Mac to boot from an external bootable medium.

1. Restart your Mac while pressing down the Command\-R keys together to enter [macOS Recovery Mode](https://iboysoft.com/mac-data-recovery/macos-recovery-mode.html) .
2. Select "Utilities" from the menu bar \> "Startup Security Utility." ![Startup Security Utility on Mac](https://iboysoft.com/images/en-howto/usb-catalina-installer-not-bootable/startup-security-utility-mac.jpg)
3. In the Allowed Boot Media section, choose "Allow booting from external or removable media." ![allow Mac boot from external media](https://iboysoft.com/images/en-howto/usb-catalina-installer-not-bootable/allow-booting-from-external-media-mac.jpg)

Now, you can restart your Mac and try to boot your Mac from the USB installer again.

### ③ Check the way you boot your Mac from the Catalina USB installer

You can compare our steps to check if your way of booting a Mac from a USB is correct or not.

1. Turn off your Mac and connect the macOS Catalina bootable USB to it.
2. Turn on your Mac and, meanwhile, press and hold the Option \(or Alt\) key until you see the bootable volumes, including the macOS Catalina bootable volume, appear on the screen.
3. Select a network. ![choose network](https://iboysoft.com/images/en-howto/usb-catalina-installer-not-bootable/choose-network.jpg)
4. Select the macOS Catalina bootable volume and press Return.
5. Choose a language.
6. Choose "Install macOS" from the macOS Utilities window. ![choose Install macOS from macOS utilities window](https://iboysoft.com/images/en-howto/usb-catalina-installer-not-bootable/install-macos-catalina.jpg)
7. Click "Continue" and follow the on\-screen guide to install macOS Catalina.

## Case 2: The Catalina USB installer is labeled as not bootable

### Re\-create the macOS Catalina bootable USB installer

The conventional method for creating a bootable USB installer involves many steps, including formatting the drive, searching for and downloading the macOS installer from the App Store, and running command\-line instructions in Terminal. This is so complex and time\-wasting, and most importantly, it is error\-prone.

Therefore, we recommend switching to using[iBoysoft DiskGeeker](https://iboysoft.com/disk-utility/). This multifunctional disk management tool can help you create a macOS Catalina bootable USB installer with a few clicks, without requiring Terminal.

Here's how:

1. Connect an empty USB drive with at least 32 GB of storage space to your Mac.
2. Free download, install, and open iBoysoft DiskGeeker on your Mac.
3. Click "Create boot disk," select a volume on the connected USB drive, and click "Select" \> "Continue." ![choose create boot disk](https://iboysoft.com/images/product-ibd/version-420/choose-create-boot-disk.jpg)
4. Select macOS Catalina from the list and click "Create boot disk" \> "OK" to start downloading the Catalina DMG file. ![choose macOS Catalina](https://iboysoft.com/images/product-ibd/version-420/create-boot-disk-choose-macos-version.jpg)
5. After the downloading process is complete, it will immediately start creating the macOS Catalina bootable USB installer.

After that, you can use the newly created macOS Catalina USB installer to boot up your target Mac.

If you insist on using Terminal to do this job, follow:[How to create a bootable USB installer for macOS](https://iboysoft.com/howto/how-to-create-a-bootable-installer-for-macos.html).

Tips:If data loss happens accidentally during booting a Mac from the bootable USB installer, recover the data with[data recovery software for Mac](https://iboysoft.com/free-mac-data-recovery.html).

## FAQ

AHere are the possible reasons: The macOS installer is incomplete or damaged. The installer was not created correctly. The Mac does not support that macOS version. Restriction from Apple Silicon startup security settings and T2 security settings. The USB drive itself is problematic or corrupted. The startup method is incorrect. The firmware is too old.

ABefore starting: Check that the Mac supports the macOS version. Ensure external booting is allowed \(for Apple Silicon and T2\-equipped Macs\). For Apple Silicon Macs: 1. Connect the bootable USB installer. 2. Shut down the Mac. 3. Press and hold the Power button until Loading startup options appears. 4. Select the USB installer and click Continue. For Intel Macs: 1. Connect the bootable USB installer. 2. Shut down the Mac. 3. Turn it on and immediately hold the Option \(⌥\) key. 4. Select the USB installer from Startup Manager and press Return.