Chosen Solution
After I upgraded my Mac to High Sierra 10.13.2 , I found out that I can’t log in my Win10. I tried to command +r and use disk utilities but it won’t help. Also I use shift+control+option+power to hold them for 45 seconds but still won’t work. Everytime I push the option button and try to log in the win system instead of mac os, it just froze there.
Sadly a dual partitioned system (Mac/Win) under High Sierra has a problem with the boot loader. This has to do with the upgrading to APFS. If Windows is important you’ll need to reformat your drive with Sierra and stick with Sierra. You’ll need to backup and restore from both environments until the APFS issues have been resolved. Your other option here is to run BootCamp within High Sierra. Unlike dual boot you’re using a virtual machine (VM) setup. Given the small size of the SSD drive you might find you’ll need to delete the Windows partition you currently have.
