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Install Mojave instead of Catalina

I have an iMac with Catalina 10.15.3. I need to install Mojave so I can do some testing. I have an external 4T hard drive that is connected and it has been erased so it is available. I do not have a time machine backup of Mojave but I did (supposedly) downloaded a Mojave installer from the app store. It is now on my hard drive in the Applications folder. It is called "Install macOS Mojave" and shows 6.05 GB.

I tried following some steps on a MacWorld site for creating a bootable version of Mojave on the external drive but when I got to the steps to enter the command string into the Terminal, it responded that it couldn't find the directory or file.

So, how can I get there from here (i.e. get Mojave installed)? Note, this is all on a separate computer that I'm trading in so I do not need to save any data.

iMac Line (2012 and Later)

Posted on Mar 16, 2020 2:44 PM

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Posted on Mar 17, 2020 5:37 AM

John - Proj wrote:

I have an iMac with Catalina 10.15.3. I need to install Mojave
It is called "Install macOS Mojave" and shows 6.05 GB.
I tried following some steps on a MacWorld site for creating a bootable version of Mojave on the external drive but when I got to the steps to enter the command string into the Terminal, it responded that it couldn't find the directory or file.
So, how can I get there from here (i.e. get Mojave installed)?
Note, this is all on a separate computer that I'm trading in so I do not need to save any data.



Yes you have the correct full Mojave installer.


Follow the instructions as posted above by D.I. Johnson for making a bootableUSB installer....

If you are having further issues—then spell them out.



I will add if you are trading in or selling you should read this for details:

What to do before you sell, give away, or trade in your Mac ...


Similar questions

4 replies
Question marked as Top-ranking reply

Mar 17, 2020 5:37 AM in response to John - Proj

John - Proj wrote:

I have an iMac with Catalina 10.15.3. I need to install Mojave
It is called "Install macOS Mojave" and shows 6.05 GB.
I tried following some steps on a MacWorld site for creating a bootable version of Mojave on the external drive but when I got to the steps to enter the command string into the Terminal, it responded that it couldn't find the directory or file.
So, how can I get there from here (i.e. get Mojave installed)?
Note, this is all on a separate computer that I'm trading in so I do not need to save any data.



Yes you have the correct full Mojave installer.


Follow the instructions as posted above by D.I. Johnson for making a bootableUSB installer....

If you are having further issues—then spell them out.



I will add if you are trading in or selling you should read this for details:

What to do before you sell, give away, or trade in your Mac ...


Mar 17, 2020 11:20 AM in response to D.I. Johnson

D.I. Johnson,

Thanks. I tried searching the Apple support website before posting but apparently I didn't put in the right search string and that's how I ended up at the MacWorld website. Turns out the MacWorld info was exactly the same but what I forgot when I tried it the first time (using the MacWorld instructions) is the command strings in Terminal must be exact. I had all the forward and back slashes correct but I didn't include the critical spaces in the command string. I guess that was a little easier to see when I looked at instructions on the Apple site. At any rate, once I got the command string correct, everything when smoothly, I got Mojave installed and I'm a happy camper. Thanks again

Mar 17, 2020 11:31 AM in response to leroydouglas

leroydouglas,

Thanks for adding your two cents. I'm trading in my old iMac to Apple. The instructions sent with the return box tell how to save my data, remove all passwords and then erase the hard drive. I did all that and thought I was good. Oops, not quite. If I hadn't decided to do my experiment with Mojave I would not have known that some of my personal data was still on my old computer's hard drive. The critical part left out of the instructions in the box was to delete the Hard Drive - Data volume, those instructions simply say, "select your hard drive volume". I have now followed the more complete instructions on the Apple website (you listed) and am much more confident my old computer is "wiped".

Install Mojave instead of Catalina

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