Redownload Archived macOS Installers to Address Expired Certificates

So, since these are identical to the app store ones, can’t earlier versions also be downloaded from the app store?

Thank you,


To some extent, it depends on what macOS your friend is running that script from as each OS has it’s own catalog and not all catalogs contain every installer.

It also depends on the model mac that one has, as there are some forked versions that are only available to macs that were introduced after a software update.

So when I run my own script in Mojave just now, I see two additional installers available:

1 041-91758 10.13.6 17G66 2019-10-19 macOS High Sierra
2 041-83630 10.15.1 19B88 2019-10-29 macOS Catalina
3 061-26589 10.14.6 18G103 2019-10-14 macOS Mojave
4 041-88800 10.14.4 18E2034 2019-10-23 macOS Mojave
6 061-26578 10.14.5 18F2059 2019-10-14 macOS Mojave

But you are correct, that unless you squirrel away an older installer, it will be difficult to go back. You can use shift-option-⌘-R to reinstall the macOS that came with your Mac, or the closest version still available.

Thanks for the note about turning off caching! – That explained why I could re-download all OS X versions from Lion to El Capitan in App Store. When I “downloaded” El Capitan there in the hope of having an easier time to do a bootable installer, I noticed the certificate was not updated … . Turning the cache off on my other computer (Mojave), I just get an error message in App Store on the Sierra machine.

Oh good—glad that note helped. I wasn’t quite sure what caching would do in this situation, but it seemed like it could cause confusion.

Still not quite sure how to make a bootable backup from the new installer though … can extract the package and find the InstallESD.dmg file, but … not urgent.

Or use DiskMakerX or Install Disk Creator.

It looks like those programs also only handles App Store downloaded systems, just like another program I have.

Of course one could start from a full system installed on an external drive, but would be nice with just the OS installer. Otherwise it is often easier to simply a clone an external drive to the internal.


Then I have no idea what you are looking for. It’s necessary to have a copy of the Installer Assistant (full installer) on a drive somewhere in order to create a bootable backup. The methods I outlined will copy that installer along with a minimal system folder to an external drive (I use USB Thumb-drives of at least 8GB, but any external will do).

The discussion was on how to create a bootable installer from the new Mac OS X El Capitan installer from Apple that we should now use: El Capitan

Apple has no advice on how to do this, nor have I seen any here or elsewhere. Pre-Sierra systems cannot be re-downloaded from the App Store with the new certificate. (But I got a full installer.) Maybe you managed to create a bootable installer yourself from the new El Capitan?

Yes, that article tells you exactly how to obtain the OS X El Capitan installer in part 4. You start by using the download link which I will repeat here: I recommend you change it’s name to “InstallMacOSX El Capitan.dmg” for easy identification, should you need it again. Then you mount the InstallMacOSX El Capitan.dmg by double-clicking it and when the window open you will see an installer called “InstallMacOSX.pkg”. Double-click that and the Installer app will open it and download the El Capitan full installer, signed with the new certificate, into your /Applications folder. If it launches, simply quit and follow the other instructions I cited to create that bootable installer.

I have not attempted to create a bootable installer myself as my current iMac won’t run it, but I have discussed it with others who have.

Yes, I was not expecting it to install the installer, but to install the macOS … but I should have read the instructions more carefully. That solved that confusion. Thanks!

Anyone having luck with downloading the full 6GB Mojave installer from the App Store? On one machine I only get a 22MB stub installer. On another machine I was able to download the full 6GB version but the installer app reports to be damaged. I re-downloaded it a few more times with the same results.

Yes, several days ago after it was first re-posted. There were lots of problems with the mirror sites that Apple CDN uses, but those have reportedly been cleared up now.

The advice I’m reading now is to clear all caches that might impact the download. Unfortunately I have no idea what those might be. Perhaps starting up in Safe Mode will take care of that. I have heard a few reports in the past of that working for uses with such constant problems.

I downloaded El Capitan from the link above and launched it to have Install OS X El in /Applications.

One thing i noticed is, InstallESD.dmg from InstallMacOSX.pkg has a different hash than in /Applications/Install OS X El Capitan. And the file size is bigger too by 1mb.

Is that normal?

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So, any suggestion on finding the old installer to create the bootable USB drive (I’m trying to resolve the SIerra installer error)?

In my haste to fix my installers I unfortunately deleted my old installer.

As far as I’ve been able to tell, it’s been permanently removed from all Apple servers. I recovered mine from Time Machine.

Apple frowns on sharing such things amongst users, but that’s the only source I’m aware of at this time. It’s too large for most sharing web sites so I suspect you will need to locate someone close by that still has one to physically copy.


Excellent suggestion to look at backups. I found an ‘old’ 10.12.5 Sierra installer, created a bootable USB with the expired installer (the createinstallmedia approach) and then as suggested copied the new installer with updated certificate to the drive.

I haven’t tested installing, but I do know that I can boot from it.

Twice I have downloaded new installers for High Sierra and El Capitan and every time they still have the expired certificates. I have removed the original downloads and moved them to the Trash - but didn’t empty the Trash. Might that be an issue?

Or is it something else?

I think I’m gonna try to do the next downloads on a newly wiped laptop and see if that has any impact. Any ideas would be welcome.

I’ve not tried in a while, has the Sierra installer issue been resolved yet?

The currently posted Sierra installer fixes the expired certificate problem.

The only remaining issue is that you won’t able to create a bootable installer on a USB Drive and Apple has told at least one user that they won’t be fixing it.

I worked around the problem by using the old installer (from my TimeMachine) to create a bootable Thumb Drive and then replaced the installer with the one currently posted.

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