Downloading macOS installers with updated signing certificates on macOS Catalina
As a follow-up to last week’s expiration of the certificate used to sign previously-released macOS installers, Apple has released re-signed macOS installers with the new certificate which is good until April 2029.
For those who archive older macOS installers, this means that the macOS installers in question will need to be re-downloaded. macOS Catalina has added some new functionality to the softwareupdate tool which can assist with this. For more details, please see below the jump.
To download the latest installer for macOS Catalina, which is currently at version 10.15.0, please run the command below with root privileges:
softwareupdate --fetch-full-installer --full-installer-version 10.15
Note: Normally the version is specified as 10.x.x, but Apple has historically listed a .0 release as 10.x. So in this case, the softwareupdate command uses 10.15 for macOS 10.15.0.
You should receive a message that the the installer is downloading and installing. In this context, the message refers to installing the macOS Installer app into the /Applications directory on the Mac.
Once the process has completed, you should receive a message that installation has completed successfully.
To verify, check to make sure there is now an Install macOS Catalina app in the /Applications directory.
To download the latest installer for macOS Mojave, please run the command below with root privileges:
softwareupdate --fetch-full-installer --full-installer-version 10.14.6
To download the latest installer for macOS High Sierra, please run the command below with root privileges:
softwareupdate --fetch-full-installer --full-installer-version 10.13.6
macOS Sierra is not available for download via the softwareupdate tool, but it is available via the Mac App Store (MAS). Apple has a KBase article, available via the link below, which shows how to access the macOS Sierra page in the MAS:
https://support.apple.com/HT208202
Update 10-28-2019:
Mike Brogan correctly points out that the KBase article is no longer linking to the MAS, but instead provides a download link to a disk image file which contains the Sierra installer.
https://twitter.com/mikebrogan/status/1188648556359348224?s=21
It also appears the Apple KBase article for upgrading to OS X El Capitan and the Apple KBase article for upgrading to OS X Yosemite have similar download links to a disk image file which contains the OS X installer.
To access the macOS Sierra page directly, please click on the link below:
https://itunes.apple.com/us/app/macos-sierra/id1127487414?ls=1&mt=12
That link should open the MAS and take you to the macOS Sierra download page.
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Der Flounder 
I run the exactly same command of macOS Catalina on 10.15 MacBook Air with root privilege, but got an error said “Update not found”. Any clue?
Unfortunately, you can’t download 10.12.6 Sierra from Catalina – says product not found. I was able to download it from 10.11.6, but it looks the packages are still using expired certs 😦
Likewise, Safari 12.1.2 is still signed using the old cert – all the other Safari packages in softwareupdate (going back to 10.7 Lion) have been resigned with the new cert – EXCEPT Safari 12.1.2.
Do you have the link of the old versions of safari?
Running into the same issue with 10.12.6… need an updated installer to repair some of our 10.12.6 machines which are suddenly booting up with a “no entry” symbol when people try to login… An overlay install has been the only way to resolve that I’ve found so far.
Sierra https://support.apple.com/en-us/HT208202
El Capitan https://support.apple.com/en-us/HT206886
Yosemite https://support.apple.com/en-us/HT210717
I believe these are the old installers. I downloaded, created install disks of each of them and get “can’t be verified and may have been corrupted or tampered with during downloading”.
Yeah, once I had that InstallOS.dmg, I found that I couldn’t run the InstallOS.pkg inside it on Catalina. Had to run it on another Sierra system I still had (it might have run on 10.14, but didn’t have one in front of me at the time) for it to create the necessary Install macOS Sierra.app needed to create the USB drive.
Multiple attempts to create the USB drive (using https://support.apple.com/en-us/HT201372, including the –applicationpath variable) from a Catalina machine results in failure: “Terminating app due to uncaught exception ‘NSInternalInconsistencyException’, reason: ‘Couldn’t posix_spawn: error 35’”
On 10.14, getting the error that the USB drive “is not a valid volume mounting point” no matter how its formatted.
Getting the same on a 10.12 machine as well… tried multiple USB drives, so not sure what I’m missing…
Dan, did you end up successfully being able to create a bootable installer for Sierra using a machine running on Sierra? I’ve tried for the last 2 months, but have had no success using Catalina.
Nope. But we found out that we could do an overlay installation of 10.14 on these machines — as this both resolved the issue and upgraded them, we’ve been doing that instead.
Suspect that the issue with downloading an old installer from App Store on a system that is running a macOS version that is newer than that is not allowed — you can’t go backwards with system installs this way — you need to boot up using an OS that is equal to or older (not newer) than the version of macOS that you’re trying to download. That’s been my experience any way. Just to double-check I just booted an older MacBook from a Mtn. Lion boot disk and the same link that didn’t work from High Sierra still doesn’t work, but this time it says that Sierra is already installed, which is not true, so no idea why it’s doing this … sure wish that there was an easy way to download any macOS installer you wanted on a system that was running any version of macOS … this simple capability is just getting so darned complex ;-(
But at least the links to the “dmg” files within the articles seem to work fine, so that’s something. Thanks very much for posting those. Any idea on where complete older installers can be found, even really old versions like 10.0 or 10.1 or 10.2. or 10.3 or 10.4 or … — found an old PowerBook that had been behind a bookcase for years recently and wanted to play around with it, and also wanted to see if I can find a complete set of installers so that can do some testing.
Thanks again…
When trying to re-download 10.15, 10.14.6 or 10.13.6 it would always fail if I used sudo. I tried 10.15 again by copying the command “softwareupdate –fetch-full-installer –full-installer-version 10.15” and by accident didn’t add sudo and it downloaded fine. I tried again with 10.14.6 and 10.13.6 and they all downloaded fine. I now have all three installers in my Applications folder on one machine. Just thought i would share.
How might you download if you are still on Mojave?
This is extremely helpful as are many of your posts. Thank you! Can you shed light on way the newly signed Mojave installer app is no longer supporting the –eraseinstall option that many of us use to erase a mac’s drive and reinstall the OS. I have downloaded the new Mojave installer with a Mac running Catalina. Then copied that installer to a mac running Mojave that I want to nuke.
With “Install macOS Mojave” in the /Applications folder on that mac to be nuked, in the past I was able to run the command: “/Applications/Install\ macOS\ Mojave.app/Contents/Resources/startosinstall –eraseinstall –newvolumename “Macintosh HD” –agreetolicense –nointeraction ” To nuke the mac and reinstall a fresh install of Mojave. That isn’t working. Console log reports from Process osinstallersetupd “NSURLCOnnection finished with error – code – 1100” which isn’t very helpful. Any Thoughts?
Expecting a full Install macOS Sierra.app, I followed the Apple link and downloaded the InstallOS.pkg file. I had an external boot drive with Sierra installed and an older Install macOS Sierra.app in the Applications folder. I booted a 2012 MBP from the external drive and erased the internal drive and ran InstallOS.pkg from the external boot drive expecting a working installer, but the install ran very quickly with no interaction. When it finished, my older Install macOS Sierra.app had been updated and has installed Sierra 10.12.6 (16G29) without a problem. My older installer was dated July 14, 2017, modified June 24, 2019 and was version 12.6.03. Next up: will it create a good USB installer?
Sierra app is no longer available in MAS.
softwareupdate –fetch-full-installer –full-installer-version 10.14.6
Will not work for me –fetch-full-installer –full-installer-version are unrecognized option
@Bart Remember you can always check the man page for a binary which should give you all the available options
You would see that all fully spelled out commands have two dashes. You are missing a ‘-‘ so its –fetch-full-installer –full-installer-version
Notice the little space between the two ‘–‘
Looks like the comments section will merge a – – to a – which is a different kind of dash
Same for me, using 2 dashes on High Sierra.
$ sudo softwareupdate –fetch-full-installer –full-installer-version 10.5
softwareupdate: unrecognized option `–fetch-full-installer’
softwareupdate: unrecognized option `–full-installer-version
Neither the usage message or man page show those options either.
The –fetch-full-installer option is only available in Catalina versions of softwareupdate:
https://scriptingosx.com/2019/10/download-a-full-install-macos-app-with-softwareupdate-in-catalina/
Does anyone know if this still works? Specifically I’m trying to download 10.14.5. I can download 10.14.6 with no issues (from Catalina 10.15.2 on an iMac 2017), but when I try 10.14.5 it either times out immediately with “Install failed with error: Update not found” or appears to start download process and stalls at around 77-83% before giving the same error code. Have been trying for about two weeks now. Any help would be greatly appreciated.
Somehow, this worked for me to install the latest release of macOS Catalina Beta… after a lot of many unsuccessful reboots and retries using the ‘normal’ update process, eventually, it started the installation… but let’s say it was quite tricky and took me the whole day to accomplish!
I am trying to create bootable USB using Sierra.app from InstallOS.dmg. Getting error – “Terminating app due to uncaught exception ‘NSInternalInconsistencyException’, reason: ‘Couldn’t posix_spawn: error 35’” as pointed out by Dan Green. Kindly suggest solution. Thanks.
macOS 10.14.6 works without any issues but unable to download the macOS 10.13.6. Any other way to download 10.13.6? Thanks.
softwareupdate –fetch-full-installer –full-installer-version 10.13.6
Downloading and installing 10.13.6 installer
Install failed with error: Update not found
Yup, I just had the same issue. Can’t get 10.13.6 to download using `softwareupdate`. Received the same error. Downloading it on a Mac running 10.12 gave me a 22MB “stub” not the full 4-5GB installer.
Oh, Apple. Why you gotta be this way?
This was not working for me, same issues with “Install failed with error: Update not found” trying to download 10.13.6 from a 2019 5k iMac (iMac 19,1). Similar problems with any version prior to 10.14.4, the original OS. Not sure if it mattered but running 10.15.4 beta (5?6?)
Back to my trusty 2015 MBP with Parallels, updated a High Sierra VM to Catalina via app store, and ran the same commands. Now 86% through downloading 10.13.6, have not tried any other versions.
So it appears this feature is still limited by the hardware. I noticed the 10.14.x and 10.15.x version do a short download before failing, so assuming is checking hardware. HTH!
Hello, does anyone know where the installers downloaded from Terminal come from?
It seems 10.15.5 broke this option 😦
If you need High Sierra through Catalina installers, you can use dosdude1’s macOS Patchers (see http://dosdude1.com/software.html ). They’re normally used for installing macOS on unsupported machines, but these patchers also offer a “Download macOS Installer” option which downloads an untouched, 1:1 original copy of the installer from Apple directly. Just download the installer and quit the patcher afterwards–no need to write a patched installer to a USB if you don’t need it.
He offers a Sierra installer but unfortunately it’s missing the installer download option. 😦