Create Bootable Disk?

[pmcdn]

Trying to downgrade from Mojave to earlier OS. I have a late 2015 iMac that I upgraded to Mojave without thinking. I tried booting with command plus are, and went through the tool to reinstall but it only offered Mojave again.

I went back to the disk utility tool and deleted the drive but now I want to put El Capitan back on for starters, but it doesn’t see a start up disk.

When I put in my formatted thumb drive, formatted, and OS X extended journal (I think), it says that that thumb drive isn’t the right, GUID, and takes me back to the disk utility tool, which gets me nowhere because I cannot partition it.

What’s the easiest way for me to create a bootable drive on my thumb drive? I also have a 2015 MacBook Pro loaded with Mojave on it.

I’ve googled the hell out of this, and I’m not coming up with a solution. Any or all help will be greatly appreciated.

Thanks!

 

[Nguyen Duc Hieu]

Trying to downgrade from Mojave to earlier OS. I have a late 2015 iMac that I upgraded to Mojave without thinking. I tried booting with command plus are, and went through the tool to reinstall but it only offered Mojave again.

I went back to the disk utility tool and deleted the drive but now I want to put El Capitan back on for starters, but it doesn’t see a start up disk.

When I put in my formatted thumb drive, formatted, and OS X extended journal (I think), it says that that thumb drive isn’t the right, GUID, and takes me back to the disk utility tool, which gets me nowhere because I cannot partition it.

What’s the easiest way for me to create a bootable drive on my thumb drive? I also have a 2015 MacBook Pro loaded with Mojave on it.

I’ve googled the hell out of this, and I’m not coming up with a solution. Any or all help will be greatly appreciated.

Thanks!

Other macOS installation options

When you install macOS from Recovery, you get the current version of the most recently installed macOS, with some exceptions:

On an Intel-based Mac, you can use Shift-Option-Command-R during startup to be offered the macOS that came with your Mac, or the closest version still available. Or you can use Option-Command-R during startup to be offered either the latest macOS that is compatible with your Mac, or in some cases the macOS that came with your Mac or the closest version still available.
If the Mac logic board was just replaced, you might be offered only the latest macOS that is compatible with your Mac.
If you just erased your entire startup disk, you might be offered only the macOS that came with your Mac, or the closest version still available.
You can also use these methods to install macOS, if the macOS is compatible with your Mac:

Use the App Store to download and install the latest macOS or an earlier macOS.
Use a USB flash drive or other secondary volume to create a bootable installer.

 

[Fishrrman]

To expand on post 2 (make it step-by-step)

1. BACK UP your data, because we're going to erase the internal drive.

2. Boot to a SPECIAL VERSION of internet recovery:
Command-SHIFT-OPTION-R
at boot

3. If you connect via wifi, you'll need your wifi password

4. The internet utilities take a while to load, so be patient while the globe spins.

5. When you get to the utilities, open disk utility

6. Check to see if there is a "view" menu. If there IS, you MUST go to it and choose "show all devices".
(If there's no view menu, skip to step 7)

7. Look at the list on the left. The topmost item should be the physical drive inside. Click on it to select it.

8. Click the erase button. For El Cap, choose "Mac OS extended with journaling enabled, GUID partition format".

9. When the erase is done, quit disk utility and open the OS installer.

10. Start "clicking through". The Mac will restart one or more times, and the screen will do dark for a minute or more, with no other indication of activity. BE PATIENT.

11. When done, you'll see the initial setup screen (choose your language). If you have the backup close by, connect it and start "clicking through".

12. When setup assistant asks if you wish to migrate from another disk or backup, YES, you want to do this. Point the way for setup assistant and give it time to digest everything.

13. You will see a list of stuff that can be migrated. I suggest you migrate it all. Again, it will take some time.

14. When the migration is done, you should see you old login screen, just as before.

Good luck.