For some users, macOS Sierra presents a lots of bugs and issues; some apps and hardware pieces are incompatible with it. In any case, you don’t want to experience Sierra if for whatever reason, it is possible to roll back from Sierra to El Capitan. In case, you are finding ways to recover data from failed Mac OS Sierra update, just visit the link to know more.
Before we explain how to do roll back from Sierra to El Capitan, let’s find out what you can’t do:
What you can do is entirely erase macOS Sierra, re-install Mac OS X El Capitan and restore your data from a Time Machine backup that you made before you downloaded the Sierra. But, if you want to continue with macOS Sierra, here are the steps to follow when Mac won't start after Sierra update.
Tutorial for how to downgrade from Mac OS Sierra to El Capitan
1. Erase macOS Sierra
You need to connect your Mac to a strong internet connection either via Ethernet connection or Wi-Fi. Ensure the connection is stable and follow the below mentioned steps:
2. Reinstall Mac OS X El Capitan
After you have deleted macOS Sierra, quit Disk utility and start reinstalling Mac OS X El Capitan by following the explained instructions here:
Now, just go ahead with the above process, agree to the terms & conditions and simply reinstall it. After the process is completed successfully, your Mac machine will restart.
3. Restore data from Time Machine
After you have downgraded to OS X El Capitan from macOS Sierra, you can easily backup your data through Time Machine. If you saved your data in Time Machine, you can use it in the present Mac OS X El Capitan by following these simple steps:
Please wait until the process is completed. Make sure you be patient, it will take some good time depending on the network speed and the amount of data that is to be transferred.