How to create a bootable disk for an older Mac? The file system on an older Mac mini (early 2009, latest supported OS 10.11) got corrupt, and disk utilities ended up in an infinity verify-can't-repair loop. Thanks to a insightful tip I could mount it on a different machine and restore my files. (I physically removed the disk and mounted it with a USB-to-SATA cable).

I proceeded to reformat the disk, and now want to install a bootable macOS on this disk.

The best action seems to follow the Apple guide "How to create a bootable installer for macOS", which requires me to download macOS 10.11 (El Capitan). It's normally hidden in the App Store, but I found the direct link. Unfortunately, I can't seem to download it on my new Mac: It gives me a warning "OS X can't be installed on "MyNewMac" because the version of macOS is too new.". I know, but don't want to run it, just install on the disk for the older Mac, so I can run it on the early 2009 Mac mini.

How to proceed?
Note: A more complete and up to date answer to this question can be found at this link: How can I download an older version of OS X/macOS?

I tried your link https://itunes.apple.com/app/os-x-el-capitan/id1147835434?mt=12 and received the following error message. Assume your error message was the same.



The answer below assumes the Mac is running High Sierra.

If you purchased El Capitan for free in the past, then you will find this recorded in your App Store account. Open the App Store application, then click on the Purchased button. Enter your username and password. If you purchased El Capitan in the passed, then El Capitan will appear in the list. You will be able to download even if the macOS is newer than El Capitan. 

If El Capitan does not appear in your list of purchases, then try to find someone who has purchased El Capitan and use their username and password.