I can't make bootable USB on 2008 iMac 2008 running El Capitan I have 2008 iMac and OS X El Capitan on it. I will make bootable USB drive for my friend, but I can't. I format my USB as Mac Os Extended and GUID parition map, then I downloaded InstallMacOSX.dmg file from apple; double click on it and I have installmacosx.pkg. (I can't find The El Capitan installer to the /Applications folder). I click on this package and I have an ALERT: &quot;OS X v10.11.6 is already installed on this computer. Use the Updates page to install the 10.11 update or if you would like to download the full OS X installer click Continue&quot;. I click continue and have to select destination disk, but when I select my external USB drive, I have the message: &quot;OS X can't be installed on this disk. macOS isn't installed&quot;. Can you help me?
OS X El Capitan has a recovery partition which is used to reinstall OS X on your Mac should you need it. Instead of using the .pkg, You can try copying the entire contents of your recovery partition to your USB. After formatting the USB as macOS Extended, go to OS X Recovery by pressing Command + R. Then, unmount all volumes except the Recovery partition and USB and go to Terminal. Then type
cp / /Volumes/USBNAME.
If you are trying to make a ready installation of OS X El Capitan, then you can use your recovery partition to reinstall OS X to a USB drive. Simply boot into OS X Recovery and select the reinstall OS X option. Select your USB drive and connect to WiFi if prompted. If you would like to install macOS Catalina on the USB, then Apple says you must upgrade your computer to macOS High Sierra to avoid issues with the firmware and in order to have access to the Install macOS Catalina application.