Hello, I'm trying to create a bootable usb with Mac Os Sierra, I tried 2 different software and it didn't work. Also I tried to use Terminal but the installation also failed.
In particular, Install Disk Creator says: An error occurred. Try ejecting the destination disk and reinserting it, or rebooting. It probably couldn't be unmounted to erase it.
What can I do?
iMac 27″ 5K, macOS 11.0
Two things spring to mind and neither are good. The Sierra Installer is corrupt and needs to re-downloaded a fresh with notation to use Safari as Other may not work. Further to Sierra on link supplied is " Safari downloads the following older installers as a disk image named InstallOS.dmg or InstallMacOSX.dmg. Open the disk image, then open the .pkg installer inside the disk image. It installs an app named Install [Version Name]. Open that app from your Applications folder to begin installing the operating system." Then try the Bootable Installer via Terminal
Second - the drive being used to make the Bootable Installer is failing and need to use another drive.
Two things spring to mind and neither are good. The Sierra Installer is corrupt and needs to re-downloaded a fresh with notation to use Safari as Other may not work. Further to Sierra on link supplied is " Safari downloads the following older installers as a disk image named InstallOS.dmg or InstallMacOSX.dmg. Open the disk image, then open the .pkg installer inside the disk image. It installs an app named Install [Version Name]. Open that app from your Applications folder to begin installing the operating system." Then try the Bootable Installer via Terminal
Second - the drive being used to make the Bootable Installer is failing and need to use another drive.
Creating a Bootable Installer of Sierra is straightforward - though can only be performed from a Computer that Qualifies to run Sierra. The Profile listed with your posting indicates iMac 27″ 5K, macOS 11.0 and may part of the failures. That or the USB Drive is not directly connect to the computer and or is too small or is filing itself.- would be best to use 16 GB and not smaller.
On the safe side - Reformat the problematic drive HFS Journaled and GUID Partition Map. Have used this Terminal Command many times and has worked - below - Give the Destination Drive Name Untitled
sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ macOS\ Sierra.app --nointeraction &&say Done
Thank you very much for your reply. I followed your advices and it failed again 😞
the error is the following:
createinstallmedia[11336:201461] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Couldn't posix_spawn: error 35'
*** First throw call stack:
(
0 CoreFoundation 0x00007fff33b35b57 __exceptionPreprocess + 250
1 libobjc.A.dylib 0x00007fff6c7e35bf objc_exception_throw + 48
2 Foundation 0x00007fff361f8f01 -[NSConcreteTask launchWithDictionary:error:] + 4993
3 Foundation 0x00007fff362227f1 +[NSTask launchedTaskWithLaunchPath:arguments:] + 146
4 createinstallmedia 0x0000000102d01968 createinstallmedia + 6504
5 libdyld.dylib 0x00007fff6d98bcc9 start + 1
6 ??? 0x0000000000000006 0x0 + 6
)
libc++abi.dylib: terminating with uncaught exception of type NSException
PS: I'm using a MacBook Air 2017 running MacOS Catalina
Isn't there an alternative way to install an older MacOS on a partition?
AFAIK the macOS 10.12 Sierra installer is broken when it comes to creating a bootable macOS 10.12 USB installer since Apple decided to hide the download link for the last year or two instead of actually fixing the installer. There is a simple fix that needs to be performed in order to create a bootable macOS 10.12 USB installer, but I don't recall the exact details. I know the fix has been mentioned on these forums a few times over the last year or two.
Unless you have software that will only work with macOS 10.12 I recommend you install macOS 10.13 High Sierra instead.
Try using another brand of USB stick since the quality of USB sticks is extremely poor.
Make sure to have a good backup before attempting to upgrade macOS just in case something else goes wrong.
FYI, you should always have frequent and regular backups.
Here is the solution that worked for me:
1- downloaded macOS High Sierra using Safari instead of my favourite browser. Infact, when I tried to download it from another browser, it failed to connect to the App Store and the download didn't start.
2- Installed it on my MacBook Air
3- I used Install Disc Created to create a bootable USB without any problem. The pen drive I've used before was ok.
So at the end of the day the copy of macOS Sierra I used was corrupt.
Many thanks for your support P. Phillips!
Thanks for your reply. I solved the issue by downloading Mac Os High Sierra using Safari instead of the browser I normally use. This allowed me to download it from the App Store very quickly. Any other browser failed to create a connection with the app store and the download couldn't start, that's why at first I opted for Mac Os Sierra, because the download started directly, without passing from the App Store. I guess that that copy of Sierra was corrupt because I eventually managed to create a bootable USB with my flash drive.
Any chance the issue is expired Apple Certificates within the Installer ? If so, disconnect from Internet and Roll the Time back on the destination computer to 2014 and run the installer.
Welcome and Thank you too :-))
Sorry to read Sierra dmg was damaged and had to use High Sierra though in the end - all worked.
FAILED to create a bootable USB
