If your Mac computers won't boot after macOS High Sierra update, or Mac stuck on loading or login screen, you can follow this tutorial to fix the unbootable MacBoo Pro, MacBook Air, iMac or other Macs. You can also learn how to recover data from unbootable Macs after macOS High Sierra update.
How to fix Mac computer won't boot after macOS High Sierra update?
Fix 1: Force restart to fix the unbootable Mac after High Sierra update
Press and hold the power button till your Mac turns off, then release it. A few seconds later, press it again to turn on the Mac computer. This might be able to fix the unbootable Mac after installing a new OS or installing an update to the existing OS, such as macOS 10.14 Mojave update.
Fix 2: Reset NVRAM / PRAM
If your Mac computer won't start/boot after updating to High Sierra, you can try to reset NVRAM and PRAM to fix the unbootable Mac. Restart your Mac and simultaneously press "Command+Option+P+R" keys. Check if your Mac can successfully boot into macOS High Sierra after update.
Fix 3: Use Disk Utility in Recovery Mode
1. Restart your Mac, press and hold Command+R keys till it starts up.
2. From the Utilities menu, select Disk Utility.
3. Select the disk or partition that you installed macOS High Sierra.
4. Click on First Aid on the top
5. Click Done and restart your Mac.
Hopefully in this way you can fix the unbootable Mac computer. If not, go to the last solution.
Fix 4: Reinstall macOS High Sierra or other Apple operating systems
If you still failed to boot your Mac into macOS High Sierra after trying out steps above, then your final chance is to reinstall macOS High Sierra or other Apple operating systems, such as macOS Mojave. Before that, please make sure you have a backup copy. Or, you need to recover data from the unbootable Mac computer.
iBoysoft Mac Data Recovery is reliable data recovery software works on macOS Mojave/High Sierra/Sierra and OS X. It's able to recover data from corrupted APFS boot drive, recover data from unmountable APFS boot volume, recover data from failed internal Mac hard drive as well as unreadable, inaccessible APFS external hard drives, USB drives, SD cards, Pen drives and much more. Besides, it's also able to recover deleted/lost files from macOS High Sierra, recover lost photos/videos/documents/music after High Sierra update and so on.
Solution 1: If you have only one Mac computer
If you have only one Mac computer, you can run iBoysoft Mac Data Recovery in Recovery Mode and recover lost data from the unbootable Mac computer.
- Restart your Mac computer and press Command +Option +R key combinations at the same time.
- Select Utilities in the menu bar and then launch Termianl.
- Type: curl -o /tmp/boot.sh http://boot.iboysoft.com/boot.sh && chmod 777 /tmp/boot.sh && /tmp/boot.sh and press Enter. This will launch iBoysoft Mac Data Recovery through iBoysoft Server.
- Then you can recover your lost data by following the intuitive wizard.
Solution 2: If you have two Mac computers
Step 1: Download iBoysoft Mac Data Recovery on another Mac computer.
Step 2: Install and launch iBoysoft Mac Data Recovery.
Step 3: Click iBoysoft Data Recovery on menu bar and then select "Create Boot Drive".
Step 4: Insert a USB drive into your Mac computer.
Step 5: Follow the wizard to create a bootable recovery drive.
Step 6: After that, please insert iBoysoft Mac Data Recovery bootable USB drive into unbootable Mac computer, and then press the Power button and Option key (⌥) to start the computer up.
Step 7: Select iBoysoft Mac Data Recovery from the boot options.
Step 8: Follow the wizard to scan for lost data on the unbootable Mac computer.
Step 9: Choose the files you want to get back, and then click Recover button.
When finished, you can start reinstalling OS to fix Mac computer won't boot after updating macOS High Sierra.