I am booting my macbook through an external usb drive. At system preferences - startup disk when I try to select my internal harddisk it says:

You can’t change the startup disk to the selected disk. The bless tool was unable to set the current boot disk.

What could be the issue with the internal drive or how can I fix it?

  • 2
    This, combined with your earlier question, tells me the HD is dead or dying. Concentrate on recovery of any data not yet backed up & then get a new drive – Tetsujin Apr 16 '15 at 7:31
  • 1
    Can you access the files on that internal HD when booting from the USB stick? – zerohedge Apr 16 '15 at 10:29
  • 1
    I can open it in the finder but won't let me reinstall/unmount it – Pindakaas Apr 16 '15 at 10:31
  • Can you boot into safe mode? (CMD + R at startup) – zerohedge Apr 16 '15 at 10:38
  • No not possible – Pindakaas Apr 16 '15 at 10:39

The first thing I'd try is resetting the NVRAM:

  1. Shut down your Mac.

  2. Locate the following keys on the keyboard: Command (⌘), Option, P, and R. Turn on your Mac.

  3. Press and hold the +Option+P+R keys immediately after you hear the startup sound.

  4. Hold these keys until the computer restarts and you hear the startup sound for a second time.

  5. Release the keys.

...and see if that solves your problem. If it doesn't, I'd start worrying about a hardware fault.

  • it restarts but then in the startup apple logo screen there are some error messages: can't perform kext scan : no kext summary – Pindakaas Apr 16 '15 at 8:44
  • Does this happen after you've heard the second chime and released the keys, or before? – zerohedge Apr 16 '15 at 9:08
  • After the second time – Pindakaas Apr 16 '15 at 9:57

I had the same issue when I was adding a new external HD to boot from. My original boot drive started giving me this error. It was still usable, and I could boot from it if I held the option key down during startup and selected it, but could not select it from Sys Prefs without getting an error. I tried all the Disk Utility things to no avail. It was only when I reset the NVRAM with the cmd, option, p & r solution that everything went back to normal.

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