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Create bootable High Sierra USB from Mojave

D

Dr. McKay

macrumors 6502a
Original poster
Jan 20, 2010
821
112
Belgium, Europe
I need to make a bootable flash drive with High Sierra. I have a 128Gb USB3 Toshiba flash drive, and I am running Mac OS Mojave on my iMac.
I've managed to download the High Sierra installer and it is now in my applications folder.

However, when I try to launch it, it says it is too old to be run on my computer (makes sense since I'm already on Mojave).
But how do I go about it then ? I have no other external drive at my disposal, except for a 2Tb USB3 HDD which is partitioned into a HFS+ partition containing miscellaneous files, and a second partition for Time Machine. No way I can erase anything on that drive...
 
Maybe I should clarify that I want to use that Toshiba flash drive as a Mac OS boot drive, to work on. I don’t just want an installer drive. I want to install High Sierra on it an be able to create a user on it, just like I would from my internal drive...
 
If you boot into internet recovery you can use disk utility to wipe the external drive and then install the version of macOS that was preinstalled on the iMac when it shipped. Then you should be able to boot into it and update to whatever version of High Sierra you want, given you're not already on it or just bought the iMac with Mojave preinstalled.
I just used this method to install macOS Catalina on an external drive so that I can install iOS 13 on my phone but don't have to worry about messing with my MacBook's internal drive.
 
OP:

You didn't tell us which Mac you have.

I don't believe you can run the High Sierra installer while you are booted up under Mojave...
IF the Mac will boot from High Sierra, the following might apply:

1. Create a bootable USB flash drive installer, as suggested above.

2. Have a SECOND flash drive on-hand.

3. Boot from the bootable flash drive installer. Connect the SECOND flash drive.

5. Open the OS installer and "aim it" at the empty 2nd flash drive.

6. Install a clean copy of High Sierra onto the flash drive.

7. When the install is done, set up a basic account on the 2nd flash drive.

You can now boot and run High Sierra from the 2nd flash drive, "right to the finder".
 
I have tried Install Disk Creator and took my chances with a 8 Gb USB2 flash drive I had lying around. High Sierra installer on the 8Gb flash drive, have formatted the Toshiba USB 3 drive as HFS+ Journaled, GUID partition table. Booted up from the 8Gb flash drive, have been able to launch the installer, but seems to be stuck. Only about a tenth of the progress bar has been filled, says 14 minutes remaining, but nothing is happening.
Mouse pointer is not frozen, I can access the menu etc.
 
Fishrrman said:
OP:

You didn't tell us which Mac you have.

I don't believe you can run the High Sierra installer while you are booted up under Mojave...
IF the Mac will boot from High Sierra, the following might apply:

1. Create a bootable USB flash drive installer, as suggested above.

2. Have a SECOND flash drive on-hand.

3. Boot from the bootable flash drive installer. Connect the SECOND flash drive.

5. Open the OS installer and "aim it" at the empty 2nd flash drive.

6. Install a clean copy of High Sierra onto the flash drive.

7. When the install is done, set up a basic account on the 2nd flash drive.

You can now boot and run High Sierra from the 2nd flash drive, "right to the finder".
Click to expand...

My iMac is a mid 2017 27 inch model, came with High Sierra installed. I also have a mid 2015 15 inch Macbook Pro, which had Yosemite as the original OS.

I've tried with 2 USB keys, one USB2 with 8Gb which I used to create the installer, and the other USB3 128Gb key to install High Sierra on.
The installer boots up just fine, but gets stuck halfway (not frozen, because when typing CMD-L, it says installation in progress). I left it there for over 2 hours, and nothing happens. Tried it on the iMac and on the Macbook Pro.
I then wiped my Time Machine partition on the external 2Tb USB3 HDD (because I want to switch from a local TM backup to a networked one, connecting the drive directly to my router instead of the iMac, and local and networked TM backups are apparently not compatible) ; I put the High Sierra installer on the newly created partition and booted up the installer, no problem. I tried it this way because I thought the problem might be that my USB2 key is too slow.
Unfortunately, it just stops at the same moment, with 14 minutes left (sometimes switches to 13 minutes). Left this one for 2 hours as well, but it just won't finish.

Only thing I can think of is that there may be a problem with my Toshiba USB3 flash drive, but it seems to work just fine when I used it for other stuff...
 
Fishrrman said:
OP:

You didn't tell us which Mac you have.

I don't believe you can run the High Sierra installer while you are booted up under Mojave...
IF the Mac will boot from High Sierra, the following might apply:

1. Create a bootable USB flash drive installer, as suggested above.

2. Have a SECOND flash drive on-hand.

3. Boot from the bootable flash drive installer. Connect the SECOND flash drive.

5. Open the OS installer and "aim it" at the empty 2nd flash drive.

6. Install a clean copy of High Sierra onto the flash drive.

7. When the install is done, set up a basic account on the 2nd flash drive.

You can now boot and run High Sierra from the 2nd flash drive, "right to the finder".
Click to expand...


Did just that, and tried a whole bunch of other ways. No go. It simply won't install, not on an external USB3 flashdrive (tried two different ones), not an external USB3 HDD, it just gets stuck at the '14 minutes left'...
Tried re-downloading the High Sierra installer from the Mac App Store, still the same thing.
I followed the instructions on Apple's site to the letter on how to create a bootable external drive, using the command line, still won't work...
Tried it with my Macbook Pro, tried it with my iMac, no luck.

I give up...
 
If the problem is getting a copy of the High Sierra installer from Apple, you can get it "elsewhere" if you look and you don't mind downloading from unofficial sources.

If you already have the High Sierra installer, have you tried using "DiskMaker X" to create the bootable flash drive?

An alternative to DiskMaker X is "Install Disk Creator" (or so I've heard).
 
Dr. McKay said:
I'm on a supported Mac, it came with High Sierra when I bought it. I've done everything by the book, no idea why it won't work...
Click to expand...
It seems you have done everything "by the book", but what the book didn't tell you was that even if making the 8GB flash installer is successful, using that 8GB flash disk to install won't work. You need to use a 16GB or bigger flash USB disk. The 8GB gets full and stalls .... forever.
At least that was what happened to me - 16gb disk works fine for High Sierra and Mojave, 8GB seems to work for Sierra (haven't tried that personally).
 
Thanks for the feedback. I’m on vacation now, will get back to you as soon as possible.
Yes, I did try diskmaker X and some other tool, as well. Did download the ‘High Sierra’ installer from another site, but that too didn’t work (same thing, stalls at 14 minutes)

I realize that the 8Gb flash drive might not work, but neither did my 128Gb flash drive, nor a 500Gb partition on an external USB3 HDD.
The Toshiba USB3 flash drive is this one :
https://www.toshiba-memory.com/products/toshiba-usb-flash-drives-transmemory-u363/
 
Still no go...
I bought another USB3 32Gb flash drive, generic brand, still the same problem.

I had given up on High Sierra, so tried Mojave last night. Tried the Mojave disk installer app, tried Disk Creator, tried the command line, no go. Tried the procedure on my Macbook Pro and on my iMac, both failed.

Basically, I need a USB key with either High Sierra or Mojave on it in order for me to keep working with 32 bit apps I need for work, since I want to upgrade my main drive to Catalina when it comes out. I need that USB key so I can use it on both my iMac and my Macbook Pro, so that I can boot into High Sierra or Mojave and where I can install the apps I need for work, without needing my internal drive.

I'm starting to think that Parallels will be my only option, since I cannot seem to be able to make an external bootable drive...
 
OP wrote in #16 above:
"Basically, I need a USB key with either High Sierra or Mojave on it in order for me to keep working with 32 bit apps I need for work, since I want to upgrade my main drive to Catalina when it comes out. I need that USB key so I can use it on both my iMac and my Macbook Pro, so that I can boot into High Sierra or Mojave and where I can install the apps I need for work, without needing my internal drive."

I'll offer you another path forward for the "32-bit issue".

Leave Mojave installed on the INTERNAL DRIVES on BOTH your iMac and MBP.
DO NOT "upgrade" them to Catalina when it comes out.
Let them continue to exist with Mojave.

Instead, install Catalina onto an EXTERNAL drive and boot and run that way if you need to fool around with Catalina.

I said "fool around" because obviously you NEED Mojave (and its 32-bit capabilities) for your "work" (which is "serious").

Again, don't upgrade to Catalina unless you have some compelling need to do so.

That's how I'm handling my own "32 bit future". I have numerous apps that are 32 bits and will never be upgrade-able. So... I'll stick with Mojave for the next few years to come, and "updates be damned".
I'll use "what works" for me, and ignore what doesn't.

One other thought:
If you absolutely, positively need an external drive that is bootable with Mojave on it, just download CarbonCopyCloner (FREE to download and use for 30 days).
Get an external USB3 drive (SSD would do best).
Then MAKE A CLONE of your existing (Mojave) OS install onto the SSD.
It will boot and run just fine that way.
This is, literally, "child's play" on the Mac.
 
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Downloaded CCC and tried to clone my internal SSD to the 128Gb Toshiba drive (I deselected Pictures, Movies and Music folders because I wouldn't have enough space on the USB drive).
Let it run overnight, ran for over 23 hours... and stalled.

I've run out of options. Only thing left to try is Parallels. Think there's a demo, so I might give it a go. But if it works, I'll need two licences, since one Parallels licence is for one Mac. That sucks.
Still, it's worth it for me, IF it works.

Curious, though, how all my attempts of creating a bootable drive and cloning my internal drive have failed...
 
bogdanw said:
Do you have Preferences - Energy Saver - "Put hard disk to sleep when possible" enabled?
Click to expand...
I'm pretty sure it's disabled, but I'll double check tonight.
Tried it on my iMac, and I set Energy settings to maximum performance. On my Macbook Pro, I leave them on default to save on battery.
It's bizarre, that I simply cannot perform a simple task like that. I don't have any problem whatsoever with anything else, hardware nor software wise.
Tried two different USB3 flash drives, tried an external USB3 HDD, always the same problem. Tried with High Sierra, and now Mojave, both downloaded from the App Store so I can't imagine the disc images being corrupt.

Don't know if there could be an app running in the background that causes a conflict.
This is what I have in my startup apps, apart from Apple's own icloud services and app store :
- Google backup
- Tiles from Freemacsoft, who als make the excellent Appcleaner
- Junos Pulse (a VPN client)

Maybe I should try removing Junos Pulse. You can't just remove from the startup items, you have to remove it completely with Appcleaner (or any other cleaner app) because it always leaves a plist file otherwise, that forces it to launch after boot-up...
 
Last edited:
Mr_Brightside_@ said:
What responses do you get when using createinstallmedia?
Click to expand...

I can create a bootable installer USB drive, which I can boot from, that's no problem. I cannot, however, install Mac OS Mojave (or High Sierra, for that matter) on an external drive which I can then use to work with, as if it were my internal drive.

I tried again yesterday, launching the Mojave installer from my Applications folder on my internal SSD on my Macbook Pro (mid 2015 15 inch, i7, 512Gb SSD, 16Gb of RAM, running an up to date version of Mojave). Selected my 32Gb USB3 thumb drive as destination, and let it run. Installation was quite quick, not taking more than 10 minutes.
It then rebooted, and I lo and behold, I got to the registration screen where I could create a user name and password, but everything was very slow and jerky. Ultimately, I succeeded in entering my username and password but after that it just gave me the 'spinning beachball' for half an hour, and then a black screen, with the mouse pointer still visible (I could still move the mouse pointer with the trackpad - this didn't work on my iMac since I use a BT mouse and keyboard).
Waited for half an hour longer but it never got to the desktop.

So, I advanced a bit further, but still no cigar. It's toying with me, I tell you, testing my patience...
 
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