How can I upgrade my 2012 iMac from macOS Mountain Lion to macOS Catalina?

andyy! wrote:

I want to upgrade step wise to mac os Catalina.

But I have so many obstacles in the path.

Network connection problems daily.

Mountain Lion is so old that it may not be able to make connections to modern https sites – including Web pages containing Apple Support articles. It also might have trouble accessing the App Store.

I think you need to do a two-step upgrade, from Mountain Lion to (El Capitan or Sierra), and then to High Sierra or Mojave or Catalina. Catalina breaks 32-bit applications (so may break many of the ones you have now – and still isn't good enough for applications from the likes of Microsoft and Adobe – but would be enough to let you run current versions of Firefox, LibreOffice, and the commercial Affinity V2 programs (Photo, Designer, Publisher).

What is the proper way to get Catalina ?

How to download and install macOS - Apple Support

• Back up the old iMac. Do NOT erase it. You will need a working OS for later steps.
• Use a modern Mac or PC to download the .DMG containing the Sierra installer and to put it onto a USB drive like a USB flash drive. This will NOT get you a bootable installer; just a USB drive with a data file on it.
• Transfer the flash drive to the old Mac and copy the .DMG file to it.
• Open (mount) the .DMG file (disk image) and run the installer inside.
• ----------
• Once you have successfully installed Sierra:
• Make a bootable clone backup (for safety and to preserve progress)
• Use the old iMac itself to access the Support article and the App Store link for Catalina in it.

Before going to all this trouble, be sure it is OK that you will not be able to run Microsoft Office / Microsoft 365, any of the Adobe applications, Turbotax, etc. If that is your goal, you will need something much newer than Catalina – and it would be time to look at replacing the whole iMac.

Andy,

A 2012 iMac cannot run Catalina, it is simply too old. Please refer to: macOS Catalina is compatible with these computers - Apple Support

As a 2012 is now 13 years old and considered obsolete (meaning it will not run current versions of Mac OS) and is vintage (meaning parts are difficult to source) it may be time to consider it's replacement.

While I know this is not what you wanted to read it's something you may want to consider rather than dedicating time and resources to vintage hardware.

rkaufmann87 wrote:

A 2012 iMac cannot run Catalina, it is simply too old. Please refer to: macOS Catalina is compatible with these computers - Apple Support

That Support document says that the Late 2012 iMacs can run Catalina!

You are correct sir, I simply misread the document. Thanks for point that out, hopefully the OP can breath a little more life into the old iMac!