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I am having an issue creating a bootable disk of Sierra. I am trying to make the bootable disk on a 2017 MacBook Air running Catalina. I have downloaded Sierra and created the installer in my applications. The bootable disk is for an older computer I am trying to restore. I have tried Install Disk Creator and it gave me the error that it couldn’t dismount my USB to erase it. The USB is a 3.0 with 64 GB. I have formatted the USB with Mac OS Extended (Journaled) and GUID Partition Map. I tried Diskmaker X and it failed as well. I then tried the Terminal route with the following: sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia –volume /Volumes/Untitled –applicationpath /Applications/Install\ macOS\ Sierra.app I got the following response: 2020-08-19 14:58:41.822 createinstallmedia[8986:81124] *** Terminating app due to uncaught exception ‘NSInternalInconsistencyException’, reason: ‘Couldn’t posix_spawn: error 35’ First throw call stack: ( 0 CoreFoundation 0x00007fff36a37b57 __exceptionPreprocess + 250 1 libobjc.A.dylib 0x00007fff6f87e5bf objc_exception_throw + 48 2 Foundation 0x00007fff390faf01 -[NSConcreteTask launchWithDictionary:error:] + 4993 3 Foundation 0x00007fff391247f1 +[NSTask launchedTaskWithLaunchPath:arguments:] + 146 4 createinstallmedia 0x0000000103b33968 createinstallmedia + 6504 5 libdyld.dylib 0x00007fff70a26cc9 start + 1 ) libc++abi.dylib: terminating with uncaught exception of type NSException Any help would be greatly appreciated. Thank you!
I have tried everything I can think of and it still won’t make a startup disk. Here are all the steps I took with their results. I have also added a picture of what I think you were looking for in disk utility.
I thank you so much for your help. This is frustrating considering I just spent quite a bit of money redoing an old computer with a new HD, Ram and battery, and now I can’t create a startup disk.
So let’s do this, after formatting the disk (which appear to have done properly). Download this file from Apple How to upgrade to macOS Sierra jump down to Step 4 and click on the Blue URL link labeled ‘Download macOS Sierra’ You’ll need to double click on it to unpack it. Take the unpacked dmg file placing a copy onto your Thumb drive. Review this guide How to create a bootable macOS Sierra installer drive to convert the file into a bootable image. That should do it! Now take the thumb drive placed in your other system and then see if it starts up under it. If not restart the system again this time press the Option (⌥) key to get to the Startup Manager then select via the arrow keys. Reference: Mac startup key combinations
