The createinstallmedia command will erase the content of your USB drive, so back up any data on the drive if it's important. Locate the Mac OS installer file in your Applications folder. Plug your USB flash drive into your Mac.

There are various ways to boot macOS. Aside from using the built-in Startup Manager, you can also boot into Verbose, Safe, and Target Disk modes. In addition to this, macOS users also have an option of picking a disk to boot the operating system from.

But let’s delve into something more specific. You’re about to find out how to boot your Mac up directly from external storage, specifically flash storage or a USB-based flash drive.

Related:Create bootable flash drive for Windows 10.

Why You Need to Boot from External Drive?

There are many occasions you may have trouble with your Mac.

• Corrupted system files and Mac crashes unexpectedly.
• Mac runs very slow with sufficient storage.
• You have deleted some system files wrongly.
• You couldn’t login to your Mac.
• Troubleshooting purposes.

Let’s begin with the obvious question here; what are the basic requirements for creating bootable USB for Mac?

How to Create Bootable USB Drive for Mac?

1. USB drive with sufficient storage space.
2. Access to a working and supported Mac.
3. Format USB to Apple supported file system.
4. Get installer file for macOS.
5. Create bootable USB.
6. Booting Mac from Startup Manager.

If you are not able to login to your Mac, you need to use Time Machine backup disk. Otherwise you should have another Mac for creating a bootable USB.

1. USB Drive

The macOS installer file is large with approximate size of 6 to 10GB depending upon the version. Also the process needs to sufficient storage space on your USB. So ensure to have at least 32GB or greater storage space on your USB drive.

Remember to copy and backup the USB since you need to delete the entire content for creating the bootable drive.

2. An Intel Based Mac

Apple transitioned to an Intel processors in 2005. In other words, if your Mac is not older than 2005, you should be fine.

3. Format USB Flash Drive to Apple File System

First, plug in your USB drive. Press “Command +Spacebar” to access Spotlight, then type “Disk Utility”. You can view the current file system of the USB drive. In our example, we have FAT32 file system which is compatible on Windows. You need to erase and format the USB to be compatible with your Mac.

Windows FAT32 USB Drive in Mac

Click on the “Erase” button on “Disk Utility” and choose the format as either APFS or Mac OS Extended. In most cases, your Mac will show the supported format by default and you don’t need to change it. On older Mac, you will see an additional scheme option, choose “GUID Partition Map”. Click on “Erase” button to continue further.

Disk Utility will delete all content on the USB and format it in the selected APFS or Mac OS Extended format.

Formatted USB Drive in Mac OS Extended File Format

4. MacOS Installer File

In order to create a bootable USB drive for Mac, you need download Mac OS installer. Open App Store on your Mac and search for the latest macOS version. Remember, App Store will only have the latest version which is macOS Mojave at this point when we write this article. Search for “macOS mojave” and click on the “Get” button.

This will start downloading the installer file to your “Applications” folder.

5. Creating USB Installer

After downloading, the installer will automatically ask you to install macOS Mojave. Simply quit the installer without starting the installation.

• At this point, ensure you have inserted the formatted USB drive, let’s say the name of the USB volume is “Boot Disk”.
• Also make sure the downloaded macOS installer file is in “Applications” folder.
• Press “Command + Spacebar” and search for “terminal” to open Terminal app.
• Copy and paste the below command in Terminal and hit enter.

sudo /Applications/Install macOS Mojave.app/Contents/Resources/createinstallmedia –volume /Volumes/Boot Disk

• You need to enter admin password to proceed further.
• Terminal will ask you to confirm erasing the volume, press Y and hit enter to confirm.

Ready to start.

To continue we need to erase the volume at /Volumes/Boot Disk.

If you wish to continue type (Y) then press return:

• Now the erase disk process will start to copy the installer file on the USB drive. After successful completion of the process, name of the USB drive will be changed similar to the installer file name like “Install macOS Mojave”.

Note that Apple discourages booting with an earlier macOS version than the version your device is shipped with.

6. Boot Mac from USB

Follow the below process to boot your Mac from bootable USB:

• Insert the bootable USB installer drive and go to “Apple Menu > Restart”.
• When your Mac restarts, press and hold the Option key till “Startup Manager” opens.
• The Startup Manager scans and lists the drives that are connected and bootable.
• Note that the Startup Manager will only list volumes that include bootable volumes. If you only see “Macintosh HD” like below then the USB drive is not connected to your Mac or not created properly with the installer file.

• Select your Wi-Fi network name from the “Choose Network…” dropdown and enter the password to connect to internet. Remember, you need to have an internet connection for installing from USB as the installer needs to get updates for your Mac from Apple’s server.
• Double click on your USB that contains the macOS installer or highlight it and press the return key.
• You will see macOS Recovery app and choose “Install macOS” option from Utilities.
• It may take long time depending upon your Mac to start booting with macOS Mojave.

Wrapping Up

As simple as the process seems, it tells you a lot about your system. For example, if a USB flash drive that contains a bootable copy of macOS doesn’t show up on the Startup manager, you may need to repair the disk permission. Also, remember to format the USB drive with a APFS or Mac OS Extended format.

That said, now you know how to boot up another version of or a copy of macOS and troubleshoot possible issues with your device.

Summary

Does your Mac not recognize a USB drive? Is the USB flash drive not showing up on Mac after inserting it in the USB port? Find solutions here. Download EaseUS Data Recovery Wizard for Mac when you want to recover data from a USB drive not recognized.

Mac Won't Recognize USB, What Should You Do?

Commonly, when you insert a USB drive in the USB port on a Mac computer, the drive will soon appear on the desktop or hide in the Finder, letting you access, view, and manage data on it. Did you come across the situation that no matter how many times you try to connect the USB drive with a Mac computer, the USB drive is not showing up anywhere? Why this time Mac won't recognize a connected USB you may wonder. Though not a usual thing, the issue of an external hard drive or flash drive not showing up on Mac happens sometimes. What should you do in this circumstance? What are the effective solutions to make your USB drive show up again?

This page basically covers all the possible fixes for USB not showing up on Mac, which also applies to the similar issues of other storage devices like an external hard drive not showing up on Mac, flash drive not showing up on Mac, SD card not showing up on Mac, etc. Take a quick glance at the main content and directly jump to the part you're most interested in.

10 Fixes for USB Not Showing Up on Mac

The reasons behind the problem of a USB device not showing up are various, including the USB port is not working, USB drive corruption, virus infection, macOS faulty, etc. So, to figure out the effective solutions for your own case, you need to take time to have some basic check, exclude the irrelevant issues, identify the potential risk, and finally solve it!

Fix 1. Change the USB-to-Mac connection way

Have you tried to restart your Mac once or twice? Before taking further measures, don't forget the most efficient way to tackle commonplace hardware glitches that arises from time to time. If this operating system restarting fails to solve the current problem, move on to check the physical connectivity issue step by step.

Step 1. Plug the USB drive out from the not working USB port and change to the other USB port. Try all the available USB ports on your Mac.

Step 2. Did you use a USB connection cable or a USB-C adapter? If yes, take the USB drive out, and directly plug it in the USB port.

Step 3. Is there the other Mac computer available to you? If yes, try to connect the USB drive to this computer. Is it showing up normally?

Step 4. For SD card owners, the common way to connect an SD card to a Mac needs a card reader. If changing the USB ports did not work, try to change a card reader for a new round of tests.

The four steps of troubleshooting a USB drive not showing up on Mac are very basic, however, quite helpful in most cases. Each step can help us exclude the issues of a bad/loose connection, a not working USB port, a lack of power, and other superficial phenomenons.

Fix 2. Change settings for Mac detecting an external hard disk on the desktop

Occasionally, your Mac has already recognized the USB flash drive but not shown it on the desktop. Thus, you should go to Finder > Preferences > General and make sure the 'External disks' option is ticked. Then you'll see the USB flash drive showing up on Mac desktop.

Fix 3. Change settings for Mac recognize an external hard disk in the Finder

Finder is the other access for us to check a connected external drive on Mac. If your flash drive or external hard drive is not showing up there, go to Finder > Preferences > Sidebar, and under Locations, you need to tick the option 'External disks'. By selecting this option, we can make sure that the connected external USB hard drive or flash drive will normally show up in the Finder.

Fix 4. Check the USB drive in System Information

When you cannot find the USB drive on the desktop or in the Finder, try to look for it in the System Information section, which is usually a hidden place for average Mac users.

Step 1. Go to Applications > Utilities > System Information.

The client uses a second connection to the FTP server when it's transferring files. Cyberduck ftp download mac. The file transfers are placed within a new window. The client supports multiple transfers at once.The configuration of this client is very easy.

Step 2. Check if the system detects the USB drive. Click 'USB' on the left panel, and you can also check the USB flash drive information.

Fix 5. Reset USB ports on Mac to detect a USB drive

Step 1. Restart Mac computer, press the Command +Option+P+R keys until the Apple logo appears.

Step 2. Press Command+Option+Esc keys to close all applications that are not responding.

Step 3. Plug the USB which is not showing up to your Mac computer. If it doesn't show up, click Apple icon and select 'Sleep'.

Step 4. Wake up the computer after a few seconds by pressing any key.

Step 5. Shut down the Mac, unplug the power cord, reattach it after 15 seconds.

If this doesn't work, we should suspect the corruption issue at this moment. Don't give up and try to do some repair by yourself.

Fix 6. Repair USB flash drive with First Aid if it doesn't show up

Step 1. Go to Applications > Utilities > Disk Utility.

1. Step 2. Select USB flash drive on the left panel of Disk Utility, and click 'First Aid' at the top toolbar and click 'Run'. Disk Utility will repair any errors on the drive automatically.

Step 3. Select the USB drive and click 'Unmount' at the top toolbar, unplug the USB and plug it back in 10-15 seconds.

Fix 7. Check and fix errors in a not recognized USB with Terminal

Step 1. Open Terminal in Utilities, type:diskutil list and press Return.

Step 2. Find the disk number of your USB flash drive, type: diskutil info disk2 and press Return. (Replace 2 with the disk number of your USB flash drive.)

Step 3. Type: diskutil eject disk 2 and press Return.

Step 4. Type: diskutil list and press Return.When the USB disappear from the Terminal list, close the window.

Step 5. Close Terminal and open Console to inspect your drive errors.

Step 6. Click 'Errors and Faults' to check if there are any errors.

Step 7. Reconnect your USB flash drive back to Mac, if no error shows up, your USB flash drive is safe.

Fix 8. Save data and reformat the not showing USB drive

Disk reformatting basically solves many hard drive issues, including the not showing up USB, particularly the time when you are able to see the USB icon but files are not showing. USB drive showing empty makes no sense, so you have to reformat the disk and make it usable again.

Note that reformatting will erase data. As long as the data matters, you need to follow the standard procedure to ensure zero data loss. [1] Download EaseUS Data Recovery Wizard for Mac, the professional Mac data recovery software, to perform a full USB drive data recovery. [2] Reformat the USB drive in Disk Utility.

To format the USB drive in Disk Utility:

Step 1. Go to Utilities and open Disk Utility.

Step 2. Select the not showing up USB flash drive in the Disk Utility sidebar.

Step 3. Click Erase on the top.

Step 4. Finish the necessary information (name, format, and scheme) to format the USB flash drive.

Fix 9. Update your macOS and firmware

Did your Mac's OS keep updating all the time? Chances are that your Mac won't recognize a USB drive, especially after a macOS update. This time, take a close look at the settings whether your Mac is up-to-date. Equally, firmware updates address a variety of hardware issues and the functionality of the USB ports could well be one of them. So, keep your software and firmware up to date will likely make the USB drive show up as normal again.

Fix 10. Send the USB drive to a repair center

Nowadays even the branded USB flash drives are not expensive. If you've tried all the suggested troubleshooting methods, the USB drive is still not showing up on Mac, you have to accept the truth that it's severely damaged and beyond your ability to repair it.

Mac won't recognize a badly damaged flash drive or external hard drive since there is no way to show it up, even temporarily, which makes the data recovery difficult. The last chance for you to rescue data is to send the broken USB drive to a specialized data recovery service center nearby, and let the professionals try their best. You need to prepare for the manual data recovery cost, which is noticeably higher than the software data recovery. Hence, always try the cost-effective plan of using EaseUS Data Recovery Wizard to scan the USB drive for the first attempt.

Step 1. 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.

Step 2. After quick scan and deep scan, all files will be presented in the left pane in the scan results.

Step 3. Select files you want to recover and click Recover Now button. Don't save the recoverable files to the USB drive itself in case of data overwriting.