Recovering data and reinstall Catalina on a MacBook 2012 after failed Sequoia installation attempt

A MacBook late 2012 at Best could run macOS 10.15 Catalina 

Attempting to " Fool " the Apple installer of macOS 15 Sequoia to run on a Non Qualifying computer is not really a good idea

There is no BIOS per se on Apple Computers 

This method will WIPE ALL Data and there is No DATA Recovery - Period.

>> Only works on Intel Based Apple Computer <<

To perform this action will require booting from a Bootable Installer. 

The Bootable Installer can Only be performed on an Apple Computer 

This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer.

Example : Bootable Installer of Catalina would have to be done on a computer that Qualifies to run Catalina

Notation: If the computer being used to perform this action is Too New or Too Old to qualify to run the version of macOS - this computer can’t be used.

Alternative is, to gain access to a Qualifying Apple Computer from a family member, friend or associate.

Shutdown computer and disconnect all external drive Except the newly created Bootable Installer.

Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive. 

It will present options >> Disk Utilities >> View >> View ALL attached Drives. 

Choose the Upper Most Drive ( not the volumes indented and list below ).

The drive normally is called Apple Media or Apple SSD - that is the drive to Erase and format as APFS with the GUID Partition Map.

Once that is done >> backup out of Disk Utilities and choose install macOS. 

Follow the prompts and it may automatically reboot several time. 

Upon a final reboot - Setup Assist will present with the newer version of macOS.

You can use Setup Asset and point it to the Time Machine Backup Drive. This is a One Time offer.

Thereafter you will need to use Migration Assist 

Notation ; Time Machine Backup, starting around macOS 10. 15 Catalina and above does not contain a Full and working Copy of the Operating System

FYI, Try a PRAM Reset (hold for at least three chimes if possible) to clear the NVRAM since that hack you used modified the NVRAM settings which is most likely why you are having trouble booting to older versions of macOS.

Also, make sure to erase the whole physical drive before installing macOS 10.15 Catalina. It is possible some hacks were also put onto hidden areas of the drive. Within Disk Utility you need to click "View" and select "Show All Devices" before the physical drives appear on the left pane of Disk Utility. Erase the whole physical drive as GUID partition and APFS (top option) if installing Catalina.

PRP_53 wrote:

@HWTech 👍

Not the usual way and truly OFF Topic

If time permits Help with this would be appreciated

iMac 2019 slow after Sequoia 15.3.1 update - Apple Community

I popped in on that thread as well.

Hi_Jinks wrote:

11. I went and bought a Mac mini m2. 16GB ram and 512GB SSD.

• The MacBook Pro (Retina, 15-inch, Mid 2012) cannot run anything earlier than Mac OS X 10.7.4 (Lion) or anything later than Catalina.
• The M2 and M2 Pro Mac minis cannot run anything earlier than Ventura.

There are no versions of macOS that are compatible with both machines. Thus there is no supported way for either machine to prepare a bootable installer for the other.

I would install Catalina.

If you later decide that you want an older OS such as Mojave or High Sierra you can do that. But since Catalina is the newest macOS version the computer can run, I'd go with that for the most recent support and greatest possible longevity of the hardware.

OP wrote " I went and bought a Mac mini m2. 16GB ram and 512GB SSD. "

OP wrote " I can download mountain line on my Mac mini. Why can’t I use that to install it onto a bootable flash drive? "

Yes, you do not what to install Mountain Lion on this M2 Mac Mini.

That does not matter, the sad reality is the Mac Mini M2 is too new

This will have to be performed from a Qualifying Computer to run the version of OS X / macOS to be made on the Bootable Installer - OS X Mountain Lion

According to Apple, to prepare a bootable installer, you need a Mac running Sierra or later that is also compatible with the version of macOS you want to put on the bootable installer.

How to download and install macOS - Apple Support

So, no compatible versions of macOS in common means no way for either to prepare a bootable installer for the other.

Hi_Jinks wrote:

11. I went and bought a Mac mini m2. 16GB ram and 512GB SSD.

12. still need my MacBooks timemachine that apparently I can’t retrieve unless it’s installed. Lovely.

If your existing Time Machine backup has not been corrupted, I believe you can use it and Migration Assistant to migrate your files from that backup disk to your new Mac. This is best done on first boot, similar to what PRP described where you get a "one time" opportunity using Setup assistant. If you have already created users and directories on the new Mac Mini, then you can still use Migration Assistant but have to take care with the user names and directories if the same user as was backed up with Time Machine has already been created on the Mac Mini. I have never done that myself because I have always used Setup Assistant on first boot, but I believe that Migration Assistant will notice this and prompt you with some options. Bottom line is that you should be able to migrate your old account and files (don't migrate applications and settings, those are best reinstalled from scratch, especially with the big jump from Catalina to Sequoia) to the new Mac Mini.

Lesson learned: what one reads on the internet (including sometimes in Apple Discussions) is not always correct, so always check and re-check. If it sounds too good to be true (Sequoia on a 2012 Mac?) it probably is not true. If it was really so easy to install Sequoia on a 2012 Mac, everyone would have done it already. Fact is, that is unsupported and the 2012 hardware and firmware is actually incompatible with operating systems newer than Catalina.

If you have trouble migrating from that backup to the new Mac, you can in fact try copying the backed up files using the Finder. It's much better to use Migration Assistant or Setup Assistant, but it is possible to manually copy files via the Finder. In some cases, people find that the files are visible on the Time Machine backup drive but are locked or have a circle with slash through them, indicating no access. The answer to that is to copy those folders and files from the Time Machine drive to your new Mac's internal drive, or an external drive mounted on the new Mac: this will work even with the no access restriction showing. If on external drive, change permissions to ignore ownership on that external volume. You will then be able to change permissions on all those copied folders and files manually (easiest way is through the Get Info window and apply changes to all files/folders within) so you can access them on your new Mac and copy them to wherever you want on the new Mac.

Hi_Jinks wrote:

No. You misunderstand. I want to install mountain lion from. My Mac mini m2 onto a usb bootable flash drive to hopefully get laptop up and running again. Can I do that? And if I do that, what should I be looking out for and/or steps.

i heard that was possible. It’s never had any problems. I feel like I lost a friend.

Sorry to contradict you

I do understand you Want ( operative word ) to make a USB Installer of Mountain Lion from and on the the M2 Mac Mini

As mentioned both by self and my good colleague @ Servant of Cats 👍

Not Possible on This Specific Computer for the reasons already presented - full stop

To make matters worse

Not even on a Microsoft Windows could you make the Mountain Lion USB Installer

So may claim it is possible

When confronted to provide verification of their success that magically disappear

Hi_Jinks wrote:

You’re right about that. A lot of great advice. The reason I am asking for clarification about whether to install Mojave or Catalina or further back was because on one of these pages here I read that the only fix was to install the operating system that it was shipped with which late 2012 would be mountain lion I believe. It’s not for any other reason. if Mojave or Catalina will work or will possibly work, I’m all for that. I just I just want it to work again. I’ll make a beautiful drive for Catalina and try that unless someone clarifies that indeed I do need to use the OS that it shipped with.

It is much easier to install macOS Mojave and Catalina than it is to install any OS before macOS 10.11. Apple has made it extremely hard to reinstall macOS 10.7 - 10.9 because I don't think you can create a USB installer for them and the online installer through Internet Recovery Mode tends to have issues even if the user is one a good fast network.

The only reason to use macOS Mojave is if you have some old 32 bit only software since macOS Catalina dropped 32 bit support. Otherwise, it is best to install the latest supported version of macOS, but even Catalina is far enough out of date that you will have issues with accessing some online resources.

@HWTech 👍

Not the usual way and truly OFF Topic

If time permits Help with this would be appreciated

iMac 2019 slow after Sequoia 15.3.1 update - Apple Community