All Apple Mac device users can simply go to App Store Software Update option to get instant official update directly from Apple for free. Apple users can also Free Download Mac OS 10.15.1 Catalina.DMG Offline Installer via Direct Link/Torrent Link posted below for manual clean installation without app store. Apple has released macOS Catalina 10.15.3 beta 2 to developers for testing. The build number is 19D62e. There are no release notes for this software update; however, it likely contains bug fixes. In this video, i have shown how to install macOS Catalina 10.15.2 on VMware On Windows 10 on an AMD Ryzen PC. If you have an FX-Series AMD processor, you may. Version 10.15.7: Resolves an issue where macOS would not automatically connect to Wi-Fi networks. Fixes an issue that could prevent files syncing through iCloud Drive. Addresses a graphic issue that may occur on iMac (Retina 5K, 27-inch, 2020) with Radeon Pro 5700 XT.

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:

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:

Mac Os Catalina 10.15 2 Download Dmg

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.

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.

macOS 10.15, code name for Catalina, is the latest operating system shipped for Mac desktop and laptops. And it is the right time to create a bootable USB install USB based on Catalina becasue the signing certificates for old version of macOS and OS X are expired soon. It means only macOS Catalina is available for future macOS install. So before the Mac goes into trouble or just want to install a fresh copy of Catalina, it is highly recommend making a bootable USB installer right now!

Looking for make a bootable USB installer for macOS Catalina for your Mac device but don't know how? Well, this article will guide you straight away with all the preparatory tips and steps to create a bootable macOS Catalina USB install drive in minutes.

Part 1: Preparation for Making a Bootable macOS Catalina Install USB

Before we get started for creating bootable macOS Catalina install USB, there are a few things we should pay attention to. This will avaoid the portential issue within the installation process.

1. An accessible Mac computer where you can download and make the bootable installation drive.

2. An USB drive with a minimum storage capacity of 16 GB. Also, it should be formatted to APFS.

3. Make sure there are enough free space on Mac. The Installer file is over 8G.

Part 2: Download a Copy of Bootable macOS Catalina Installer

There are two ways to download macOS Catalina 10.15. The most common way is via Mac App Store or you can use the third-party apps, which is a good alternative if the operation could not completed successful in App store. This happens a lot at least on my MacBook Pro.

Step 1: Open App Store on Mac and type 'Catalina' in search bar.

Step 2: The macOS Catalina install app appears in search result and click 'Get' button. Now the Software Update interface shows up, asking if you want to download macOS Catalina.

Step 3: Confirm the operation and the system starts to download macOS Catalina Installer. Now wait for the task to be completed. You will find the an app named Install macOS Catalina in Application folder. That's the file for OS installation.

Mac Os Catalina 10.15 2 Download Full

Part 3: Create Bootable macOS Catalina USB Using DMG Editor

If you have download macOS Catalina DMG file, then UUByte DMG Editor is the only tool you can find to make a macOS bootable USB from DMG disk image. However, if you downlaoded the Catalina install app from App store, please skip this part and read the following recommendations.

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Step 1: Click above button to download a copy of UUByte DMG Editor.

Step 2: Install the app on a Windows PC or Mac and insert an USB drive into the computer.

Step 3: There are three options you can see from the main window. Click 'Burn' button in this step for creating bootable USB.

Step 4: Click 'Browse' button to import the macOS Catalina dmg file into DMG Editor and select the correct USB drive, where the dmg file will be copied to. Now, click 'Burn' button to initial the task.

Step 5: There is a progress bard associated to this process and you can see the estimated time. Wait untile you get 'burning completely' message. This means the burning process is finished successfully and the USB is now bootable!

Eject the USB drive from Mac and insert it to the device where macOS needs to be installed. And follow the instructions to install macOS when the installation wizard is loaded.

Part 4: Create Bootable macOS Catalina USB Using Install Disk Creator

How To Download Catalina 10.15

When you get the macOS 10.15 Catalina install file, the next move is to burn the file to USB. However, it is not a single copy-paste. The bootable information should be written to USB at the same time. So you must use third-party apps to get it done. At here, we are using Install Disk Creator, one of the best GUI programs to make a bootable USB from macOS.

Step 1: Click this link to download Install Disk Creator.

Step 2: Unzip the file on Mac and drag the app icon to Application folder. Open the app from Launchpad and insert an USB drive into Mac.

Step 3: From the app interface, click the USB drive name you just installed and add macOS Catalina Install App file in Application folder. Then click 'Create Installer' to write boot information and copy installation files to USB.

Part 5: Create Bootable macOS Catalina Install USB via Patcher App

You might get this error when trying to download macOS Catalina from App Store. And that's why we need to use third-party apps to replace Mac App Store.

macOS Catalina Patcher is a great utility for creating USB flash drive installer for Mac devices that don't support macOS Catalina. The Patcher tool is available with several new updates and features. However, these updates are not applicable for all the Mac users to upgrade their devices to the latest desktop iOS version. This tool is used for the unofficial installation of macOS Catalina on Macs that wouldn’t normally support an upgrade to Catalina.

Step 1: Connect the USB to Mac and format it to OS X Extended with Disk Utility app.

Mac Os Catalina 10.15 2 Download Free

Step 2: Download the latest version of macOS Catalina Patcher. Go to Tools and click 'Download a Copy' to download the installer app.

Step 3: It will take some while to complete the download as its size is around 8GB. When the download is finished, open macOS Catalina Patcher app and click 'Browse a copy' option to add the downloaded installer file (Install macOS Catalina) in Application folder. Then choose the target USB drive and start the copying installation files to USB.

Step 4: Reboot Mac and hold on to the Option button. Startup Manager will appear on the screen. Nowm use the arrow keys to choose the bootable USB flash drive and click on Return.

Step 5: Open Disk Utility app and format the hard drive to APFS. From the Install macOS screen, select the hard drive on Mac to install the OS.

Step 6: As the installation process is done, shut down the Mac, and reboot back to the install USB drive. This is to ensure post-install patches on that device so that Catalina supports the system.

Step 7: Returning to macOS Recovery environment, hit 'macOS Post Install'. The installer will automatically choose all the accurate patches needed for your device, by default. Then hit Apply Patches and let the process complete. and allow the process to complete. After applying the patches, choose 'Force Cache Rebuild' and hit Restart. Now your device will reboot, where you can easily start the macOS Catalina installation.

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Part 6: Make Bootable macOS Catalina Install USB Using Terminal

Another choice to create a bootable macOS USB is through Terminal app. It is completely free and there is no need to install addition apps. However, it takes more time to figure out how it works.

Step 1: Download a copy of macOS Catalina according to the above section.

Step 2: Head to Applications folder. Then right-click on the macOS Catalina Install app icon and pick Show Package Contents. Access Contents and go to Resources folder.

Step 3: Open Terminal app and enter 'sudo' command.

Step 4: Drag the createinstallmedia to Terminal window through the Finder location as shown in Step 4.

Step 5: Type 'volume' and put a space. Head over to Finder -> Go -> Go to Folder, enter '/Volumes' and hit Go.

Step 6: Insert the USB drive to the Mac device, which will then be displayed in Finder window.

Step 7: Fetch the volume of the flash drive to Terminal with a drag-and-drop. Hit Return from keyboard to give in the entire command. Then type your password when notified.

Step 8: When prompted, enter 'y' to proceed followed by hitting return from the keyboard. Now the installation erases all content on USB and the installer files will then be copied to the drive. The process will only take a little while to complete.

Summary

Hopefully, both the tips were helpful in guiding you on how to make bootable macOS Catalina on Mac. However, it is best to go with macOS Catalina Patcher app if your Mac device is compatible with Catalina 101.15 version and only needs a bootable USB drive to install the OS.