Since installing High Sierra I’ve had trouble booting into Mac OS X from Windows 10.
I use a 2016 MacBook Pro, run closed, hooked up to two external monitors.
When I restart Windows, I hold down the alt key to select the startup disk and select the Mac drive.
The next step is that I have to enter my password to unlock FileVault.
After the disk seems it unlock, the boot process stops on a black screen, then the fans go silent and the Mac stops responding. I’ve left for periods exceeding 15 minutes just to make sure it wasn’t thinking about booting.
If I force a restart by holding down the power button, the startup chime sounds twice in rapid succession, then boot up continues.
However, sometimes the external monitors don’t get a signal, but the MacBook screen works.
And sometimes - not always - I have to unplug a USB hub for the reboot to continue. (The hub has a keyboard, mouse and a couple of USB cables in it for charging random gadgets.)
Once started the Mac runs normally.
EDIT: At no time do any error messages appear.
Resetting the PRAM and SMC doesn’t help with this.
Any suggestions for a fix? It doesn’t seem to be a critical error, but it’s annoying.
If you need more details, please say so in a comment.