Creating a Bootable Installer for MacOS

MacInWin said:

Rod, what I would venture had happened, if there was any time between the copy to the USB drive and your attempt to re-install was that the OS had been updated to a later point update, so that the installer now looked "old" to the system. If it was bang, bang, then maybe not, but that's about all I can think to cause what you saw.

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Yes, there were some weeks in between. Still at the time I thought it should still work, leaving me to update after installation. BUT the difference may have been the it was the installer, as apposed to a bootable installer created with DiskmakerX or Terminal. I have had no trouble with bootable macOS installers made that way more than a year before.


Sent from my ageing iPad Mini iOS 9.3.5 Mac-Forums

Yes, if you are booted from a newer version the installer application won't run against the boot drive. But if you are booted from an external, no matter what is on the internal, it can be replaced by an older version. If the internal has been converted to APFS, it will require repartitioning back to HFS+ to do that, but it can be done.

Yes, I see now how that can be done. The saved installers I have cloned would just need to be converted to bootable installers, or would they? If the device was booted from a clone and the installer was Ron with the target as the HD would that work I wonder?
Oh by the way I'm a little out of circulation at the moment, came down with Dengue Fever. Not much fun I can assure you.

Rod Sprague said:

Yes, I see now how that can be done. The saved installers I have cloned would just need to be converted to bootable installers, or would they? If the device was booted from a clone and the installer was Ron with the target as the HD would that work I wonder?

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It should work from a clone, but that might be a bit dicey. I don't know if the check for version is made before the target drive is identified or not. If the test is against the boot drive, a clone won't work. The DiskmakerX process installs a version of the OS on the thumb drive that is compatible with the desired installer. (I wonder if it actually takes the system FROM the installer?)

Oh by the way I'm a little out of circulation at the moment, came down with Dengue Fever. Not much fun I can assure you.

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Ugh! Get well soon!

One tidbit I have just come across when using a USB Flash drive to install macOS is that one needs to have an internet connection active.
Not to download the installer but to run any firmware updates if required.

Until now I thought when one used a USB Flash drive to install macOS, an internet connection was not required.

Use the bootable installer

After creating the bootable installer, follow these steps to use it.

Connect the bootable installer to a compatible Mac.
Use Startup Manager or Startup Disk preferences to select the bootable installer as the startup disk, then start up from it. Your Mac will start up to macOS Recovery.
Learn about selecting a startup disk, including what to do if your Mac doesn't start up from it.
Choose your language, if prompted.
A bootable installer doesn't download macOS from the Internet, but it does require the Internet to get information specific to your Mac model, such as firmware updates. If you need to connect to a Wi-Fi network, use the Wi-Fi menu in the menu bar.
Select Install macOS (or Install OS X) from the Utilities window, then click Continue and follow the onscreen instructions.

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Where does that quote come from? I've done installs from a bootable thumb drive with no internet before. I do agree that for some upgrades there were firmware updates (Mojave had one, for example) but I don't think that was universally so.

MacInWin said:

Where does that quote come from? I've done installs from a bootable thumb drive with no internet before. I do agree that for some upgrades there were firmware updates (Mojave had one, for example) but I don't think that was universally so.

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Apple support page
https://support.apple.com/en-ca/HT201372
Right towards the end

Interesting. I've never used that command from Apple to create an installer. Wonder if they add in the internet check with the mothership for firmware as a part of that? Would be like them to do that to avoid any issues if the firmware isn't at the correct release. And needing an Internet connection to use their process sort of defeats the purpose of a bootable installer. Part of the usefulness of an installer is to get a machine going again, no matter what. Wonder what the error message would be if there was no internet?

@Rod

Oh by the way I'm a little out of circulation at the moment, came down with Dengue Fever. Not much fun I can assure you.

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Take care and look after yourself Rod, that is not pleasant I've been told.





- Patrick
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Rod Sprague said:

Oh by the way I'm a little out of circulation at the moment, came down with Dengue Fever. Not much fun I can assure you.

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You will never hear me complain about coming down with the common cold again.

Well it's all kinda relative. In 6 months I will have forgotten how bloody awful it was an"man flu" will seem like a big deal. Today it would be a minor inconvenience.


Sent from my iPhone

I am the original O/P of this thread and thought I would report how I fared. Again, what I was trying to do was to install High Sierra as the operating system in a virtual machine created using Parallels. I spent hours trying to create a bootable flash drive, following all of the suggestions made in this thread. Of course, beofre I even opened this thread I had asked the question on the Parallels forums and was directed to create the bootable flash drive with High SIerra on it. I was about to give up when hunting through the Parallels menus one last time I found a well hidden option to create a new virtaul machine using High Sierra. Exactly what I had want ed to do all along. It took an hour or so and all done. Of course I'm glad it's done and really appreciate all the help I've receved here but I literally spent more than 20 hours on this before I found the hidden menu item. Ugh!

Anyway, job done and thanks again.