So, you updated macOS on your new MacBook, iMac or Mac Mini because you had an annoying
bug but now you find yourself with even worse bugs? Well, unfortunately there is not a whole
lot I can do to help you right now, but what I can do is help prepare you for the next
update by showing you how to create a bootable flash drive so you can downgrade later, if
needed.
Hey, I’m Jerry and if you are a current Mac user you may have noticed some bugs in
the last couple of years. And let’s face it, it’s a computer and software moves fast
these days so bugs a gonna’ happen. Some bugs are not so bad like Bluetooth disconnects
and some are downright awful like computers not being able to boot up after connecting
certain USB docks. And of course, issues with external displays not turning on or coming
up in a weird resolution. Apple has made it a little more difficult to download previous
copies of macOS after new versions are released so in this video, we are going to look at
how to create a bootable flash drive of your current version of MacOS, just in case you
need it after upgrading. And at the end I will show you how you can revert to a previous
Major MacOS release if your computer came with something other than what you are running
right now. For example, if your computer came with Catalina originally and you have updated
to Big Sur.
To create a bootable flash drive of the current version of MacOS you are going to need a flash
drive that is at least 16GB, and we are going to erase the whole drive in the process. The
one I like for this is the SanDisk 64GB Ultra Dual Drive which has a USB A and USB C side
and is pretty speedy. They have a 32Gb version for $10 and a 64Gb version for $15 and you
can find a link to those in the description below.
Next, you need to download the current version of Mac OS from the Mac App Store which, unfortunately,
is 11.2.3 at this moment…………Now, you have to be patient because the download will
probably take a while depending on your internet connection.
Once the download completes the MacOS install will start automatically but instead of going
through the install we are going to quit the install app and you can see the Install MacOS
Big Sur app inside the Application folder on the Mac.
Next we want to open up the terminal application and we are going to copy and paste the create
media command which you can find in an Apple support article which I will Link in the description
below.
We are going to be creating a Big Sur install disk, so we want to use the Big Sur command.
What this is telling the Mac to do is use elevated permissions and use the create install
media tool to copy files to the drive you want.
You need to be sure to change the name of the drive to what the actual name of your
USB drive is. In my case it is “flashdrive”.
If you are prompted to give terminal permissions click allow and move on.
Hit the enter button when ready and type in your admin password when prompted. Then re-type
it because you messed up. Type Y and hit enter to agree to wiping the
flash drive
The tool will format and copy the install files over to the USB drive.
This process will take at least a few minutes depending on the speed of your USB drive.
After the copy, the create install media tool will make the drive bootable….and when complete,
you now have a bootable USB drive that you can use with your Mac in recovery mode to
re-install this version of MacOS.
Just for my own Sanity I like to create a folder in the root directory and name it the
version of MacOS this is, for easy reference.
Now, what I will be doing going forward is creating a new flash drive for each version
of MacOS and have a couple lying around just in case I need to go back. I have 3 of the
SanDisk drives now and you can wrap them with tape and write the version on each one so
you don’t get them confused.
As a bonus, you can now copy that Install macOS Big Sur application to another drive
or backup somewhere just in case, and you will have it if you need it.
Now what we want to do is boot the Mac into recovery mode and erase the Mac. …..At this
point I guess I should tell you that to downgrade means that you will actually need to wipe
your disk on the Mac. This will erase all data and after the install you can restore
your files and apps from a time machine backup or some other type of backup.
To erase an M1 Mac you need to boot into recovery mode by holding down the power button from
Shutdown
You will see a prompt to continue holding for startup options
Then loading startup options
Click on Options and then continue.
You will be prompted to enter your account password so do that and hit Continue.
To wipe the disk, we need to open up disk utility. Go to the View Menu and select Show
All Devices.
Click the APFS container that is above Macintosh HD and then click on Erase…………..And
erase.
You will get a prompt about Erasing your Mac and just follow the prompts and reboot when
it tells you to.
When the computer reboots the Mac needs to activate like an iOS device so you will need
to connect to Wifi …………………and if you had find my Mac enabled you will need
to enter your Apple ID and password.
At this point if you continue with the install you will be installing from the internet so
you want to shut down and insert the USB drive you created.
Now you can boot into the startup options again then
choose to boot from your install disk so you can install the OS from the USB drive instead
of over the internet.
I found that you actually need to erase the disk again so quit the installer and open
up disk utility.
Show all devices
Click on the APFS container and erase again.
Now we can quit disk utility and start the installation!
Follow all the prompts and select your disk for install location and follow some more
prompts.
Now somewhere between 20 and 60 minutes you are good to go and can set up the Mac just
like it was brand new but is now running the MacOS version you installed.
That wasn’t so bad, right???
Now there are a couple of differences with Intel Macs. To boot into your flash drive
with an intel Mac you will need to hold down the Option key then you can select your disk.
If you have an intel Mac with a T2 Chip you actually need to change the boot security
settings before you can boot into the flash drive you created.
To do that enter recovery mode by holding Command + R when booting and then type in
the admin password when prompted.
Go to the Utilities menu and select Startup security utility.
Enter the user password again.
Select the Box for allow Booting from external or removable media. And now you can reboot
into the install media, wipe the disk and install macOS.
OK, so that is how you create an install disk with the current version of MacOS, boot up
into that install media, wipe the internal drive, and install Mac OS. Having a backup
copy of previous versions of MacOS can be a benefit as you can see and useful in case
you have issues after updating to a newer version. Yes, restoring from backup or reinstalling
apps can be a pain in the butt, but if you are suffering from a bug that affects your
workflow then downgrading MacOS may be the only option.
Now I did say at the beginning that I would show you how you can revert to a previous
Major MacOS release like from Big Sur to Catalina. This will only work if your Mac is Intel based
came with the previous major release. For example you have a 2019 or 2020 iMac that
came installed with Catalina and after upgrading to Big Sur you decided you want to go back
to Catalina.
To do this you can boot into recovery mode again but this time hold down Shift + Option
+ Command + R on boot. You will need to connect to wifi or ethernet and this will boot your
Mac up into the Major MacOS release that your computer shipped with. You will need to follow
the prompts and erase your disk but when you are all done you will have a fresh install
of a different version of MacOS.
SO, I hope that these tips were useful and maybe they will help you out going forward
when dealing with MacOS issues from updates. Let me know below if this is something you
plan on doing or if you any other great tips to share. ……………………….If you
are going to reinstall MacOS you want to make sure you have a good backup and one way to
do that is to back up your Macs with Synology and if you need a little help check out this
video right over here. ……Hit the thumbs up button if you liked it, hit subscribe if
you want and I’ll see you next time.