OS X Installation USB Not Detected – How to Fix OS X Installation USB Not Detected in Startup Disk Selection

bootbootable-diskmacbook prostartupusb

I have a MacBook Pro 8.2. Recently I have download Sierra and Yosemite, and am currently running El Capitan.
enter image description here

And I created a bootable USB for OS X Yosemite with DiskMaker X 6, in case Sierra goes wrong.

OSX X and DiskMaker

But when I try to check the USB, it's not on Startup Disk. I tried the option key on mac boot, but the USB is not there.

USB not detected on Startup Disk

I'm using SanDisk Cruzer Glide Media, here the USB details.

USB Install Disk on Finder
USB
USB Volume

Best Answer

From the last image you posted, the window says "Bootable: No". From the screenshot you posted of the files on the USB, this doesn't look like a standard bootable OS X USB. For Yosemite, you could try using Terminal (I'm not sure how Terminal would handle the periods and dashes in your USB's name, so here are the instructions if your USB is named Untitled):

Note that this process automatically erases and formats the USB before moving the files (it normally will confirm this with you), but I like to erase it myself before I do this as a precaution.

sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Yosemite.app

After the process finishes, I believe the USB is named "Install OS X Yosemite"

Source: https://support.apple.com/en-us/HT201372

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