Bootable Usb Drive Not Detected Mac


The fact that it works on one machine reassures us that the USB is in good shape - so probably you just need to make adjustments to accommodate the macbook. 1) You may need to reset P/NVRAM to let the bootable USB be recognized - here's the link.

  1. Mac Doesn't Recognize External Drive
  2. Usb Drive Not Showing Up
  3. Mac Does Not Recognize Usb
  4. Bootable Usb Drive Not Detected Mac
  5. Bootable Usb Drive Not Detected Mac Pro

Create Bootable USB for Mac on Windows 10, Mac and Windows file system is completely different, so you are not able to create bootable USB for Mac with PowerShell, CMD or Rufus.If you remembered, till MacOS sierra the Apple file system was Hackintosh, but MacOS 10.13 High Sierra has the technology of Apple Filesystem. Remove your external drive and all other USB devices except keyboard and mouse. If your system does not boot you may try to repair the drive using Single User Mode. Mac OS X: How to start up in single-user or verbose mode - Apple Support. Reboot holding down CMD+S. At the hashtag prompt (#) type. By default the USB thumb drive’s format is FAT32. You need to first reformat it to GUID with a journaled file system (HFS+) Then use the installer setup script to properly bless the drive.

Active1 year, 3 months ago

I created a Yosemite boot USB, from the App Store version 10.10.1.

When I hold option during Boot, the USB drive doesn't show up on the menu.

I have an aluminium MBP, bought in 2009. It is the full body aluminium with the Superdrive.

Per Apple, this is my machine:

The only drives I see when holding down option are Macintosh HD and Recovery. When I try to run recovery, it runs for a little and then goes to a 'no' symbol, with the spinner still spinning. I am concerned that the HD may be dead/dying, but I don't want to jump to that conclusion yet.

How do I either boot to my USB, or just get a restore done?

I have already successfully backed up my files. I just want to restore the machine.

Edit 1

I made the USB Boot drive from this guide:

Specifically choice number 1, where I downloaded the OS from the App Store and ran the terminal commands on a pre-formatted USB drive.

Edit 2

Below you will see the Disk Utility for the USB drive. Not sure how to tell if it is a Boot disk or not.


Edit 3

The below screenshot shows EFI in Debug mode in Disk Utility.

For what it's worth, when I plug in this drive into my working MBP, I see the 'Install OS X Yosemite' get mounted in Finder.

Edit 4

Here is a screenshot of the 'Startup Disk' option within 'System Preferences' on my working MBP that has the Bootable USB plugged in - which proves that it was properly created, I believe. You can check the screenshot to confirm though.

Mac Doesn't Recognize External Drive

Edit 5

Output from bless --info... command:

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You might try resetting the pram on your mac.I understand that startup disk settings are stored there.

If the disk is bootable on other Macs, it stands to reason that it should boot on this one.

You can reset the pram by doing the following:

  1. Shut down the Mac.
  2. Locate the following four keys: option,command, p and r. You'll need them in the next step.
  3. Power on the Mac, then immediately hold option, command, p and r.You need to do this before the grey screen appears.
  4. Hold down the keys until you hear the startup sound twice, then release them.
  5. Plug in the bootable USB stick, restart the Mac, and hold option.

I can't guarantee that it'll work, but it won't hurt, so it's worth a try.


I just ran into this as well. When booting from a USB disk that seemed to be bootable, it would display a 'no' symbol ( e.g. ⃠ ...) after trying to boot into it and would then boot into the OS. I tried wulfderay's suggestion (the currently voted answer) to reset the pram and it didn't help.

I came across this installation tutorial and figured out that #5 in Step 1 of creating the drive had been wrong in my case. It's important to create the partition as 'GUID Partition Table' rather than either of the other two. Mine was previously 'Master Boot Record' as a partition scheme.

I'm guessing this could be the edge case that a few of us have run into. I confirmed the SHA of my Yosemite download and used the same one to re-create the bootable USB, so this was the only difference.


Something similar has occurred to me before but then I identified that the .dmg of the OS X file was damaged which made the created bootable USB useless. Please make sure you check the SHA1 hash of the downloaded dmg with someone else to rule this possibility out.

Jash JacobJash Jacob
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Only thing that worked for me was to create the same Yosemite boot disk on a firewire drive.

MacPro Desktop Tower: OS X v10.9.5; 2x3.2GHz Quad Core Intel Xeon, 14GM 800 MHz DDR2, MacPro3,1.

Usb Drive Not Showing Up

David C.David C.

After booting with the Option method, plug in the USB drive after the existing disks appear. I think this relates to protecting the system from USB viruses: you're normally only allowed to connect the drive after the system is powered-on... this is my logic anyway!

Danny VanderbylDanny Vanderbyl

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Mac Does Not Recognize Usb

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Active3 years, 2 months ago

I had problem with the hard drive of my 13' MacBook Pro 2009. I decided to use the opportunity to upgrade to an SSD. I replaced it with a 480GB SSD.

Following this article: Create a bootable installer for OS X, I created bootable USB with El Capitan. The USB works with the computer I created it on.

On my upgraded Macbook, normal power-on ends with grey screen with flashing folder icon, as expected - there is no OS there.

When I plug the USB drive in and hold the Option key, expected menu with choice of bootable devices does not show. There is the booting sound, the screen turns white with cursor on. The cursor responds to the touch pad but no booting menu appears.

Bootable Usb Drive Not Detected Mac

I don't know how to troubleshoot the issue.

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Bootable Usb Drive Not Detected Mac Pro


The Problem is most likely that the USB Drive was not properly formated and is missing the EFI Partition. You could check via the Terminal by using 'diskutil':

The Result is a list of all Drives and their partions. A bootable USB Drive should have a separate partition like this:

The easiest solution would be using a third party tool. You should try again using the Freeware 'DiskMaker X'. It formats and creates a bootable USB Drive with the OSX-Installer in a very easy and reliable manner.


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