install mojave on second harddisc, can't download installer because Catalina

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Level 4

2,558 points

install mojave on second harddisc, can't download installer because Catalina

Hello.

Since my mac (MacMini late 2014, 10.15.1) is utterly failing me, I need to find a way to downgrade to Mojave.

I tried more or less everything that comes to mind to boot into a usb-stick usb-harddrive, but since I upgraded to Catalina, the shutdown-process crashes the mac every time. And then, it just does not take keyboard-shortcuts during start-up.

So no start-up disc selection, no recovery mode, or target-disc mode, or whatever would have been helpful. (Setting this in system-preferences doesn't help either)

Flatly attempting to download the mojave-installer is being flatly denied (Software being "too old"—It's like «I'm sorry Dave, I'm afraid you just can't do that»)

So, I'm kind of like locked-in.

What can I do, apart from grilling/nuking/drilling holes into the mac?

What happens if I

sudo rm*

in terminal?

anyone?

Mac mini, macOS 10.15

Posted on Dec 6, 2019 1:59 AM

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Answer 1

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HWTech

Level 9

60,284 points

Dec 7, 2019 2:16 AM in response to QuickPost

Are you using an Apple USB keyboard to boot into Internet Recovery Mode? Sometimes Apple wireless keyboards and non-Apple keyboards may not work correctly.

If you have a failing hard drive in the computer, then it can very well interfere with various boot modes. You may need to remove or disconnect the internal hard drive to see if that solves the problem of booting into other modes.

However since Catalina won't let you download Mojave from the App Store, you do need to download the Mojave installer from a Mac running an older version of macOS. You can either boot the computer into Internet Recovery Mode using Command + Option + Shift + R to boot the original macOS which shipped with the computer (Yosemite) or you can download the El Capitan installer while running Catalina since the El Capitan installer can be downloaded outside the App Store. Then create a bootable El Capitan USB installer using these instructions (after first running the downloaded app in order to extract the actual El Capitan installer to the Applications folder):

https://support.apple.com/en-us/HT201372

FYI, I recently did stumble across an unofficial way to download the individual pieces of various macOS installers from outside the App Store and still direct from Apple, but I cannot find the third party website with the references and the link.

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Answer 2

david braun Author

Level 4

2,558 points

Dec 7, 2019 7:10 AM in response to HWTech

HWTech,

I finally managed to get Mojave onto the mini. Boy, was that an odyssey, I felt a bit like

Yes, it is a Apple wireless keyboard. Haven't got no USB-Keyboards around.

Not sure wether the disc is faring well, I guess it is just slow, as is the whole system—with 8GB soldered ROM it's not that much of a powerhouse. I felt a bit like Sir Bedevere the Wise in front of the french occupied castle.

In the end, it was a mix of the "unofficial way" (I used http://dosdude1.com/software.html unofficial patcher to get a copy of the installer) and apple's guide to create a bootable usb-device with terminal that worked.

There was NO WAY of getting a full installer of Mojave. My computers are either running catalina already or are too old to run Mojave. (So, no download through App-Store/System-Preferences from apple at all). This, and the keyboards weird behavior were driving me really mad.

But as I said, I got it done.

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