I’m trying to sell a 2009 MacbookPro. It’s the model MacbookPro5.5 and Apple supports macOS El Capitan 10.11 as latest available version.

• El Capitan Installer App

I’ve wiped all data from the installed SSD and had to boot from an external disk. Now I’ve got two problems:

1. I’ve only got a Mac with Big Sur and Apple Silicon. I cannot use the package installer from the download provided by Apple to create the installer App for El Capitan. However, I need access to the installer so that I’m able to use the createinstallmedia command.
2. The 2009 MacbookPro is already wiped and has only access to the recovery mode. You cannot execute the package installer in Recovery Mode to extract the media.

Download El Capitan from the Mac App Store. Head over to your existing OS X environment running 10.9 or later and open the Mac App Store. Search for 'El Capitan' and click Download. The download is completely free if you're running OS X 10.9+. Wait for the download to finish (this could take some time). Format the USB Drive. OS X El Capitan Installer. Official OS X El Capitan Installer from the Mac App Store. Un-archive the zip archive and you will get the app Installer. A bootable ISO or bootable USB can be made from this installer. Instructions on how to do that are on the Internet/Youtube.

Luckily I’ve found this blog post from Chris Warrick who explained how to extract the installer App from the package:

1. Attach an external Disk which contains the downloaded pkg from Apple. You’ll need enough space on that Disk to extract the pkg and it needs to be writeable
2. Open the Terminal from inside the Recovery Mode
3. Go to the mounted volume
4. Extract the package:

Now we can try to create the install media from the installer app. Make sure you’ve attach another disk which can be overwritten by the installer. In this example its named „MyBlankUSBDrive“:

The InstallESD.dmg image is missing, which we’ll need to add to the right location:

Now we’ll have a valid installation medium which can be used to start the installer from. You can reboot from that disk and should be able to install El Capitan.

However, I’ve encountered another annoying issue which caused the installer to fail:

El Capitan Installer cannot be verified

Oh great… On to the next commands you can try from the Terminal inside the Recovery OS:

1. installer -pkg /Volumes/Mac OS X Install DVD/Packages/OSInstall.mpkg -target /Volumes/'XXX' where XXX is the name of the disk you’re installing to.
2. Wait for the installation to say it’s complete. You will not see any sort of progress display.

El Capitan Installer App

Great, you’ve got El Capitan installed! Devil may cry 1 pc full version. Apple had some issues with certificates and people found a way to either use the above commands for installation or you’ll have to tinker with your Macs time settings so that the signature is valid again. I would have expected that Apple resigned all installers so I wouldn’t have to use these commands at all but doesn’t look like they did.