macOS Sierra is the latest and updated version of Mac that comprises of many outstanding features but still issues at different stage continues to bother Mac users. After successfully installing macOS Sierra some users complaining it get stuck at the reboot. MacBook/iMac open up with a white screen with an Apple logo and simply macOS Sierra won't start up after update. If you are getting the same error need not to be disappointed as here you will find solution to fix macOS Sierra update problems following white screen on reboot:
- Restart the Mac >> Hold down Command, Option, P and R to reset the NVRAM.
- Reset SMC (System Management Controller).
- Now shut down Mac >> Unplug all cables from Mac.
- Wait for some minutes and plug the cables
- Now again start up the Mac system.
- Try to boot Mac in Safe Mode(done by pressing shut down and start again holding shift key)
- Mac has least 9 GB of free space(make sure).
- Remove all third-party Kexts, extensions and Antivirus apps.
Hope following the same step given above you have successfully resolve macOS Sierra won't start up after update issues. The step need experienced and hence are advised to take help of technical person to avoid any mistake as it may result in data loss. In case this very critical situation of data loss happens while performing the operation then need not to be disappointed as using Mac Data Recovery Software you can easily get back lost data happens while fixing macOS Sierra won't start up after update issues.