Chosen Solution
I had purchased new iMac retina 5k display machine builed OS is macOS Sierra but in that FCP 7 is not working proper so that I wanna to degrade the OS in El Capitan.Please help
If your system came with MacOS Sierra you may have a hard time rolling it back to El Capitan as Apple updated the systems firmware within this OS update, so I’m not sure it will allow you access to the App Store’s copy of El Capitan. If you have a second system which is still running El Capitan you should be able to down load the OS installer and setup a bootable OS installer thumb drive. Be aware you will need to fully wipe the system drive to install the older OS. So anything on your system now will be lost so make sure you have a good backup. Here’s the steps to create the installer drive: How to make a bootable OS X 10.11 El Capitan installer drive Frankly, I would first see if the newer version of FCP X (10.3) works for you. I’m not sure if rolling back the OS to use the older version of FCP will work with the newer hardware. I know! Dammed if you do, and dammed if you don’t ;-{ Apple has you in a tight spot. Is the reason you don’t want to upgrade related to the redesign or of a given feature (tool) you have now you don’t want to loose in FCP?
The only way I know how to go about it would be to put that computer in target disk mode and then erase the Drive then do a fresh install like it were a new drive. If you were just to try and install the OS El Capitan you wont be able to you’ll always get the prohibitory sign. you could also take the Drive out of the computer and put it in a sled or you could access DiskUtility form the Sierra installer.
