Hi.
I’ve created the bootable flash drive using Etcher. I ran into the same problem as another gentleman in this forum with having to erase, reformatted, erase again, reformatted again, etc.
Long story short, I can boot Ubuntu on my newer MacBook Air from the flash drive but my Macbook Pro doesn’t seem to see the flash drive when I power up or restart and hold the Option key down. What am I missing?
Thank you!
Hi - I had the same problem - apparently some of the older MacBooks don’t see the USB thumb drives at boot up - if you can, try burning the iso file onto a DVD -then power up holding down the option key (with the DVD in) - that worked for me. Good Luck
That’s a good tip @groovedog, thank you! It has been ages since I actually utilized optical disks.
@Mlmccabe, the above appears to be a good option!
I’m on it first thing in the morning!
Thank you both for your quick response. Wish me luck!
You got this! As long as you don’t try to install Big Sur on your MacBook first! That seems to negate external boot up devices.
Thanks for the vote of confidence! You lost me on the Big Sur But I’ll be sure to avoid anything that even sounds similar!
Never mind that! I thought another user was able to install Big Sur on an older MacBook and lost the ability to boot from USB. I guess my eyes are either playing tricks on me or I’m all over the place! 
Welcome to MY world! haha
Help please. I hope am not messing up some unspoken protocol in forum communications by piping up in this thread for another MacBook.**
I got in my hands my son’s souped up MacBook Pro 09 since yesterday. Am excited to dig in but two things make me hesitate to do the Linux Bogie attempt.**
I noticed this Mac has an NVIDIA card which seems to present challenges. Do I need to prepare for this NVIDIA card in some way to avoid NVIDIA related glitches?
USB vs CD boot option. Seems like going the CD option is prudent so I will have to figure out how to do burn a bootable version of Linux Bogie on my external CD drive.
Not a worry and welcome @BittiBrightLight!
The Nvidia may produce some issues for some users, not everyone. I run with an Nvidia card and I’m happy as a bee!
I would recommend you download and install POP!_OS, which is based on Ubuntu. It’s primary installation medium comes with Nvidia drivers, so you will avoid any trouble having to install them afterwards. Though Ubuntu does the same thing once it detects the card.
If you decide to go with POP!_OS, you can download its Nvidia option.
As for the DVD, it would appear that older Macs favor it as a boot option as opposed to USB. If you have a thumb drive available, start from it and use a DVD disk as a failsafe. 
Thank you Vasileios, I appreciate the advice. Will give it a shot just like you recommend.
It sounds like Pop!_OS has drivers for Nvidia and so would be a good place to start. I have been curious with this distro too. Thank you!
My pleasure, and enjoy the beginning of your journey! I’ll be around if anything arises. 
Thank you Vasileios!
So just to clarify…I have a USB drive that I downloaded with Pop_OS with the Nvidia driver.
I had to find my new discs to have on hand just in case. So I went to prepare what I understood to be a bootable DVD to insert if the Mac Pro does not recognize the USB first.
I have an external drive that I plugged into my primary MacBook (not the one I am going to overhaul) to copy the same Pop_OS plus driver that already is in my downloaded file folder and thought I could just click and copy onto the DVD that is in the external but it does not appear so. Nothing happened. What am I missing? Am confident my external drive can Read and Write. Any suggestions?
You’re welcome @BittiBrightLight!
The way you can burn an ISO to a DVD is to Control-Click on the ISO file and select the “Burn to Superdrive” option.
An ISO file is basically a disk image, thus it has to be restored sector-by-sector, something which a simple copy cannot do.
Once the burn process is complete, you’ll have yourself a bootable disk.
I have an early 2011 13" Macbook Pro that also would not recognize the flash drive. I was able to install Linux using the optical drive, however after that, the drive failed, probably because it hadn’t been used in used in years and I suddenly fired it up! Anyway, I wanted to check out another Linux distro to see if I liked it. So I tried again to see if I could get my Macbook Pro to read the flash drive. I found a process that worked for me so it might work for you as well.
You will need to reset the SMC as part of this process.
Turn off your machine and put the USB flashdrive in a USB port.
Be sure to keep the computer’s power adapter plugged in.
Press at the same time: Shift = Option = Control one the left side, and the Power button on the right. Hold for about 10 seconds, then release.
Turn your machine back on with the power button and immediately push and hold the Option key until the BIOS menu comes up. You should see both your hard drive and the USB drive called EFI.
Bummer. The above did not work either. It seemed to ignore the Shift-Option-Controll part and just kept rebooting. I am determined to get this to work so any other suggestions you may have would be greatly appreciated.
Thank you, thank you, thank you!
Ah ok! Is that the same with the USB prep too? I downloaded the file from the System 76 onto my Mac download folder and then just copied that file onto my USB drive. Does that mean it is not a bootable copy then?
Thank you! What is the SMC?
For the USB to become bootable, you’ll need to flash it with Balena’s Etcher (which follows a sector-by-sector ISO expansion directly into your USB).
You can download it at:
Ok! Glad my process is slow as I attempt to do this in my down times. It is allowing for me to move in a measured approach not to mention apparently I am more cautious than I knew! LOL It may pay off yet. Thank you again Vasileios! Probably won’t get to it until Sun morning.