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.
Correctly connect your USB flash drive to your Mac. Launch EaseUS Data Recovery Wizard for Mac. Start selecting the flash drive and click 'Scan' to let the software search lost files on it. After a quick scan and deep scan, all files will be presented in the left panel in the scan results. Download macOS Catalina 10.15 Installer with macOS Catalina Patcher Although it may appear easy to try out the conventional approach of downloading macOS update in Software Update, there are a few known issues on old Macs shipped in 2013 or earlier, meaning the download progress can not be completed successfully.
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:
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:
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:
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:
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:
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.
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.
Enjoy your fresh installation of macOS 10.15 Catalina.
In the guide, we will learn How to Create macOS Catalina Bootable Installer for Clean Installation. With macOS Catalina Bootable Installer you can simply use it to install macOS Catalina on your MAC. The steps are pretty easy, so you can simply sit back and relax and read this guide on How to Create macOS Catalina Bootable Installer for Clean Installation.
For Windows PC, you can use this guide- How To Create macOS Catalina Bootable USB on Windows: 4 Easy Steps (+Video Tutorial)
As you can see, the update is very democratic. Even the old computers seven years ago got a new version of macOS.
You can get the latest version of macOS Catalina from the Apple App Store.
Or, you can download it from the links provided below.
After the download is complete, do not proceed to install the macOS. Instead, close the installer and go to your application and look out for the installer file.
NOTE: The macOS Catalina Installer File must be present in your application folder to proceed with this tutorial.
To create a macOS Catalina Bootable Installer file, we will be using Terminal from the Applications with the help of a macOS Catalina Installer File.
Now, insert your USB drive or the external drive into the USB port. Before proceeding with the installation, we need to format the USB drive. Now, open the Disk Utility and click on your pen drive and click Erase.
Title: USBFlashDrive
Format: Mac OS X Extended (Journaled).
Scheme: GUID Partition Map.
Once the USB disk has been erased, close the disk Utility and open the Terminal from Applications or Launchpad.
Type the following command.
Note: USBFlashDrive at the end of the comment is the name of the USD drive that you have kept.
Enter your password and wait for the process to finish.
If you are using a Windows PC, you can use this guide- How To Create macOS Catalina Bootable USB on Windows: 4 Easy Steps (+Video Tutorial)
It was all about How to Create macOS Catalina Bootable Installer for Clean Installation. You can also make a bootable installer for macOS Catalina on Windows, but it needs a lot of time. Here is the guide that you can use- How To Create macOS Catalina Bootable USB on Windows: 4 Easy Steps (+Video Tutorial). In Mac, it has some easy actions to be carried out. If you face any problems, don’t be afraid to leave comments in the comment section below. Here are some Common macOS Catalina Problems and Solutions: 11 Key Errors and their Fix
You can also read: How to Speed Up macOS Catalina? 7 Easy Methods