I have a 2012 classic MacBook Pro that crashed the other day when waking from sleep. On reboot, I got the dreaded missing boot volume indicator. Rebooting with the option key showed no available boot partitions.
I reset NVRAM (and just for kicks the SMC). This had no effect.
Booting into Internet Recovery showed no obvious problems in Disk Utility: the drive (an aftermarket SSD installed years ago) was there and tested just fine. First aid on the disk did not fix the boot issue. When trying to select a startup disk, the internal drive was not on the list. From terminal, I could navigate the drive just fine and copy files, no problem.
I reinstalled MacOS. During the setup process, the machine rebooted and when it did, I got the same missing boot volume indicator. Rebooting holding the Option key, however, showed the boot drive. I selected Macintosh HD and Setup continued. The machine was fine. However, overnight it did not go to sleep properly after copying some additional files and the battery drained to 0. On waking up, I again got the missing boot volume icon. Rebooting with option held down shows the internal SSD and the machine boots fine.
So, how can I get my MacBook Pro to correctly and automatically boot off of the internal hard drive every time without having to hold down the option key? The computer is shared, and not everybody who uses it is going to remember to do that.
Best Answer
It may be worth you resetting your NVRAM.
Resetting the NVRAM
Here’s how to reset the NVRAM on your MBP:
Shut down your machine. Yes, a full shutdown, not just logging out.
Press the power button and then press the command option P R keys. You have to make sure you press these keys before the gray screen appears or it won’t work.
Hold those keys down until your Mac reboots again (i.e. a 2nd time) and you’ve heard the startup chime twice.
Let go of the keys and let your MBP reboot normally.
Note: When you log back in you may need to readjust some of your system preferences (e.g. speaker volume, screen resolution, startup disk selection, time zone information, etc). As a minimum I would check your Startup Disk settings.