3 weeks ago my hard drive failed so I bought a new one. (Macbook pro late 2011) 5 days ago, the new one flashed prohibitory sign, flashing folder with question mark. Every once in a while I could get it to desktop, but I would reboot, and back into the error. I reinstalled the OS through a USB, but still get the error. Is there a good chance it's the sata cable that needs to be replaced?

3 Answers 3


Try an erase and install, instead of just reinstalling OS X.

  1. Back up your files and boot into an external install media (not the Recovery HD).
  2. Open Disk Utility, select the internal disk and repartition it to 1 partition.
  3. Install OS X normally, then restore your files.

Flashing folder with question mark means that your mac can not find OS to boot. It's either it can not find some files needed in the early stages of boot up process, or can't find boot volume, or can't find the hard drive.

Before destroying all your data try reassigning your boot partition in Startup Disk preferences.

If that doesn't help check your cables. You simply might have not plugged them in firmly enough or there might be some dust in there that prevents good connection.

Check an article on the Apple KB for more options: A flashing question mark appears when you start your Mac.

  • Which files needed in the early stages of boot up process are you referring to?
    – VH-NZZ
    May 23, 2014 at 20:48
  • @okiharaherbst Usually files on the UEFI boot volume but also might be a kernel. May 24, 2014 at 12:14

First, you need to isolate the problem. Put the internal hardrive in a casing and connect it to your laptop through USB. Then boot up the OS X in this configuration by holding down OPTION key. If everything is smooth after a couple of hours, the problem is definitely SATA cable.

I have a 2011 13' MBP (A1278) and the cable broke a year ago. From what I read, the cable from this year (Parts No. 821-1226-A) is particularly faulty. You can replace it with the next iteration (821-1480-A). The latter is wider and longer, but it fits into older machines.

  • I have a related problem, but I want to clarify one point to make sure it's not something different. If the SATA cable is bad, is it possible that the OS will run correctly? In my case, the system has the boot problem 9/10 times, but once I get it to boot then all seems good until the next reboot. (I guess I would normally expect a failing SATA cable to cause some sort of problems during normal usage.)
    – Eric Marsh
    May 27, 2015 at 9:03

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