Was trying to instal el capitan on my macbook, the installation starts and after a few minutes stops and a messaging saying the os x could'nt be install on the computer, please contact the software editor to get help. I called apple and they said they can't give me any tech support, i guess cause my computer is too 'old'. If your macOS Sierra won't install or you face the same problem with other versions, then don't worry. In this guide, we will teach what to do when macOS could not be installed on your computer. Restart and Reinstall Mac. Check Mac Date & Time. Free Up Mac Space. Unfortunately, I do not have a 'startup disk' either and thus I am not sure how to go about installing OS X El Capitan at this time. The instructions says 'If possible, back up and reformat the target disk before installing'. I do have External Hard disk that I can use to create a backup using Time Machine, but I don't know what to do after that.

Start up from macOS Recovery

Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:

Apple silicon

Turn on your Mac and continue to press and hold the power button until you see the startup options window. Click the gear icon labeled Options, then click Continue.

Intel processor

Make sure that your Mac has a connection to the internet. Then turn on your Mac and immediately press and hold Command (⌘)-R until you see an Apple logo or other image.

If you're asked to select a user you know the password for, select the user, click Next, then enter their administrator password.

Reinstall macOS

Select Reinstall macOS from the utilities window in macOS Recovery, then click Continue and follow the onscreen instructions.

El Capitan Could Not Be Installed On Your Computer

Follow these guidelines during installation:

  • If the installer asks to unlock your disk, enter the password you use to log in to your Mac.
  • If the installer doesn't see your disk, or it says that it can't install on your computer or volume, you might need to erase your disk first.
  • If the installer offers you the choice between installing on Macintosh HD or Macintosh HD - Data, choose Macintosh HD.
  • Allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac might restart and show a progress bar several times, and the screen might be empty for minutes at a time.

After installation is complete, your Mac might restart to a setup assistant. If you're selling, trading in, or giving away your Mac, press Command-Q to quit the assistant without completing setup. Then click Shut Down. When the new owner starts up the Mac, they can use their own information to complete setup.

Other macOS installation options

Install Os X 10.11

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: If you use Shift-Option-Command-R during startup, you're offered the macOS that came with your Mac, or the closest version still available. If you use Option-Command-R during startup, in most cases you're offered the latest macOS that is compatible with your Mac. Otherwise you're offered the macOS that came with your Mac, or the closest version still available.
  • If the Mac logic board was just replaced, you may be offered only the latest macOS that is compatible with your Mac. If you just erased your entire startup disk, you may 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:

El Capitan Failed To Install

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