iMac with new SSD (1TB) not restoring from backup (old drive was 3TB Fusion drive) and not accessing App Store to upgrade OS

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iMac with new SSD (1TB) not restoring from backup (old drive was 3TB Fusion drive) and not accessing App Store to upgrade OS

Hi,

A number of issues.

I just installed a new SSD in my late-2012 iMac (27" Intel EMC2546) because the iMac had started behaving oddly for a week and then not starting up at all....Recovery mode told me a disk error.

Anyway, new SSD is installed and screen and everything seems to work....but there are problems....firstly, I need to format and instal an OS. So, after erasing and partitioning as per Mac OS Extended (Journaled) I go back into in Recovery Mode, but:

cannot restore from backup....it just freezes on (re)startup (which is unsurprising because the old Fusion Drive was 3TB and the new SSD is 1TB....it doesn't have room....so I erase again and start again.
also, the only option given to reinstall OS is the original Mountain Lion OS. Before I installed the new SSD I think it had Mojave on it.
With Mountain Lion installed, I cannot seem to connect to the App Store in order to upgrade , nor can I open Safari to do an upgrade via a browser (see pic)

4.Nor can I seem to use Migration Assistant to transfer an OS that downloaded to my M1 Mac and then transfer by wifi...the M1 Macbook Pro is not even showing up (see pic)

5. I did manage to use the backup to restore some files and applications, but none are working, as you can see in the dock in that first picture (because Mountain Lion is so darned old)

Ultimately, I just want to know how I can get Mojave back on to the machine. I'm thinking, if I can somehow get an OS onto an external harddrive, I can then plug that into the iMac...but my M1 Macbook pro won't let me. From this page, for example

How to download and install macOS – Apple Support (UK)

If I click on Mojave there it just tells me it's not compatible (with my M1 Macbook Pro) so I can't download it. Is it worth me trying to find the Mojave install dmg file on a third party site?? Safe enough?

Any other advice?? I've been at this since 3pm (well, the taking apart of the iMac started then) and it's now 9.30pm...it's so tedious.

Any help much appreciated.

Thanks,

GK

iMac 27″

Posted on May 1, 2024 1:31 PM

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Answer 1

Best reply

HWTech

Level 9

56,168 points

May 2, 2024 9:29 AM in response to gkmach1ne

Either try booting into Internet Recovery Mode using Command + Option + R to attempt to access the online Catalina installer, or you will need to upgrade in steps by next downloading & installing macOS 10.11 El Capitan, then upgrading to Mojave. The choice is yours. If you cannot download the macOS 10.11 installer while booted from Mountain Lion, then you will need to download the El Capitan installer using any other computer/OS which can access the Internet, then transfer the .dmg file to the iMac followed by running the .pkg file within the mounted .dmg file to extract the real installer into the Applications folder where you then need to launch it.

If you want Mojave instead of Catalina, then once you have Catalina installed through Internet Recovery Mode you can create a bootable macOS 10.14 Mojave USB installer, then boot the Mojave USB installer to perform a final clean install.

Create a bootable installer for macOS - Apple Support

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