Step by step, how do i revert to el capitan from my current catalina? I have an install flash drive with el capitan. But when I go through the process I am not offered to install it on my main harddrive. It only shows the flash drive on that screen. Some have said format the imac first before inserting the flash drive. But that option makes me nervous. I don't want to end up with no el capitan AND no catalina.
Before attempting, make a Time Machine Backup while still in Catalina
USB Installation & Wipe and Install
- ALL DATA including the Recovery Volume will be lost- there is No Recovery of any Data - period. -
To perform this action will require booting from a Bootable Installer.
This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer. Example : Bootable Installer of El Capitan would have to be done on a computer that Qualifies to run El Capitan
Once that is done read on for preparing the Destination computer >>
Only works on Intel Based Apple Computers.
Extra Special Notation regarding the Touch ID equipped Apple Computer. About Startup Security Utility and Must Enable from Recovery Mode the ability to boot from External Drive Before Attempting
1 - Shutdown computer and disconnect all external drive Except the newly created Bootable Installer.
2- Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive.
3 - It will present options >> Disk Utilities >> View >> View ALL attached Drives.
4 - Choose the Upper Most Drive ( not the volumes indented and list below ).
5 - The drive normally is called Apple Media or Apple SSD - that is the drive to Erase and format as HFS Journaled with the GUID Partition Map.
6 - Once that is done >> backup out of Disk Utilities and choose install macOS.
7 - Follow the prompts and it may automatically reboot several time.
8 - Upon a final reboot - Setup Assist will present with the newer version of macOS.
Before attempting, make a Time Machine Backup while still in Catalina
USB Installation & Wipe and Install
- ALL DATA including the Recovery Volume will be lost- there is No Recovery of any Data - period. -
To perform this action will require booting from a Bootable Installer.
This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer. Example : Bootable Installer of El Capitan would have to be done on a computer that Qualifies to run El Capitan
Once that is done read on for preparing the Destination computer >>
Only works on Intel Based Apple Computers.
Extra Special Notation regarding the Touch ID equipped Apple Computer. About Startup Security Utility and Must Enable from Recovery Mode the ability to boot from External Drive Before Attempting
1 - Shutdown computer and disconnect all external drive Except the newly created Bootable Installer.
2- Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive.
3 - It will present options >> Disk Utilities >> View >> View ALL attached Drives.
4 - Choose the Upper Most Drive ( not the volumes indented and list below ).
5 - The drive normally is called Apple Media or Apple SSD - that is the drive to Erase and format as HFS Journaled with the GUID Partition Map.
6 - Once that is done >> backup out of Disk Utilities and choose install macOS.
7 - Follow the prompts and it may automatically reboot several time.
8 - Upon a final reboot - Setup Assist will present with the newer version of macOS.
Very complete and totally correct. Apparently one can install onto a blank disk, but cannot install El Capitan over an existing copy of Catalina. Thank you for the help.
Welcome and thank you too.
Reverting to El Capitan from (current) Catalina
