I have a1gb ssd thumb (usb) drive and want to place a bootable Sierra installer on it:
MacBook Pro 15″, macOS 10.13
First of all you would need a larger USB flash drive, 1GB is not big enough it needs to be 8GBs or larger.
Here is how to download the installer disk image and then create the Install macOS Sierra.app.
If you do have an operating system on your mac and it is functioning then you can download
Sierra using this method.
Click on this link,
How to get old versions of macOS – Apple Support
Go to Download OS and click on macOS Sierra 10.12
This downloads InstallOS.dmg to your Downloads folder.
The next section can only be done on a mac that is capable of running Sierra,
a mac that came preinstalled with an OS later than Sierra will refuse to do the next bit.
When downloaded open to get InstallOS.pkg, double-click on
that and an installation window will open, read and follow the prompts,
this does not install Sierra but uses the InstallOS.pkg to create the
Install macOS Sierra.app which you will find in your Applications folder.
(If the installation window asks which disk you want to install to, you must pick
the disk that you are booted to at the time. Not any internal or external disk that
you want to eventually install Sierra on, that is for later.)
There is a problem with making a bootable USB installer with the Install macOS Sierra.app
where it returns an error Volumes/<USBname> is not a valid mount point. There is a workaround.
With Install macOS Sierra.app in your Applications folder open Terminal.
Paste in this command
sudo plutil -replace CFBundleShortVersionString -string "12.6.03" /Applications/Install\ macOS\ Sierra.app/Contents/Info.plist
press return
enter your password
press return
now paste in the createinstallmedia command for Sierra where MyVolume can be replaced with the name of your USB stick
If your USB name has more than one word separated by spaces you would need to type it in as
/The\ USB\ Name
sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\ Sierra.app
press return
follow the prompts
This will automatically reformat the disk as Mac OS Extended (APFS does not work for Sierra),
after some initial feedback on screen it will fall silent, don't worry it is still working.
It takes about 20-30 minutes to make the USB flash drive bootable.
Now it is time to make a full back up of your mac before you do anything else.
After you have made the backup you are ready to boot to the bootable USB.
Restart your mac while pressing and holding down the option/ alt key.
After a couple of minutes you will see the Startup Manager, select the USB and press Return.
When you have booted up to the USB you will see a Utilities panel, select Disk Utility and press Continue.
Highlight the Disk not any indented Volumes in the left hand column.
Click Erase.
Give the Disk a name.
Format: Mac OS Extended (Journaled)
Scheme: GUID Partition Map.
Click Erase.
When Done quit Disk Utility.
Click on Install OS press Continue.
The installation process should start up follow the prompts.
After you have installed Sierra and you have set your mac up
you can then use Time Machine to restore only your personal data
from the backup you made earlier.
Do not restore any system or library settings as this will put High Sierra back on your mac,
do not restore any apps either as this will put HiGh Sierra versions of the apps back on your
mac and these will not run in Sierra.
First of all you would need a larger USB flash drive, 1GB is not big enough it needs to be 8GBs or larger.
Here is how to download the installer disk image and then create the Install macOS Sierra.app.
If you do have an operating system on your mac and it is functioning then you can download
Sierra using this method.
Click on this link,
How to get old versions of macOS – Apple Support
Go to Download OS and click on macOS Sierra 10.12
This downloads InstallOS.dmg to your Downloads folder.
The next section can only be done on a mac that is capable of running Sierra,
a mac that came preinstalled with an OS later than Sierra will refuse to do the next bit.
When downloaded open to get InstallOS.pkg, double-click on
that and an installation window will open, read and follow the prompts,
this does not install Sierra but uses the InstallOS.pkg to create the
Install macOS Sierra.app which you will find in your Applications folder.
(If the installation window asks which disk you want to install to, you must pick
the disk that you are booted to at the time. Not any internal or external disk that
you want to eventually install Sierra on, that is for later.)
There is a problem with making a bootable USB installer with the Install macOS Sierra.app
where it returns an error Volumes/<USBname> is not a valid mount point. There is a workaround.
With Install macOS Sierra.app in your Applications folder open Terminal.
Paste in this command
sudo plutil -replace CFBundleShortVersionString -string "12.6.03" /Applications/Install\ macOS\ Sierra.app/Contents/Info.plist
press return
enter your password
press return
now paste in the createinstallmedia command for Sierra where MyVolume can be replaced with the name of your USB stick
If your USB name has more than one word separated by spaces you would need to type it in as
/The\ USB\ Name
sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\ Sierra.app
press return
follow the prompts
This will automatically reformat the disk as Mac OS Extended (APFS does not work for Sierra),
after some initial feedback on screen it will fall silent, don't worry it is still working.
It takes about 20-30 minutes to make the USB flash drive bootable.
Now it is time to make a full back up of your mac before you do anything else.
After you have made the backup you are ready to boot to the bootable USB.
Restart your mac while pressing and holding down the option/ alt key.
After a couple of minutes you will see the Startup Manager, select the USB and press Return.
When you have booted up to the USB you will see a Utilities panel, select Disk Utility and press Continue.
Highlight the Disk not any indented Volumes in the left hand column.
Click Erase.
Give the Disk a name.
Format: Mac OS Extended (Journaled)
Scheme: GUID Partition Map.
Click Erase.
When Done quit Disk Utility.
Click on Install OS press Continue.
The installation process should start up follow the prompts.
After you have installed Sierra and you have set your mac up
you can then use Time Machine to restore only your personal data
from the backup you made earlier.
Do not restore any system or library settings as this will put High Sierra back on your mac,
do not restore any apps either as this will put HiGh Sierra versions of the apps back on your
mac and these will not run in Sierra.
Eau Rouge - Thanks so much for your reply, which appears to be complete and coherent! I haven’t had a chance to try it yet, due to a bunch of stuff, but I have a 1tb usb drive and I ‘ll get to it in the next couple of days. Thanks so much for your help!
Best,
Stefan
Download sierra bootable installer