Whether you’re a first-time Mac user or a longtime advocate, few sights are scarier than the dreaded flashing question mark.
For those of you lucky enough never to have seen it, it appears immediately after you power on your computer. Instead of seeing the Apple logo (or in the old days, a smiling Mac), you’re simply presented with a flashing question mark, staring at you as though the computer forgot its singular purpose.
The ramifications can range from trifling to fatal for the computer. In this article, I will discuss what the flashing question mark means, how it can occur, and what you can do to fix it.
Understanding the Question (Mark)
When you see a flashing question mark, here is what your computer is saying to you: “I can’t find any operating systems to boot from. I don’t know what to do.”
Unfortunately, your Mac neither tells you this nor anything else that is remotely helpful, which means it is up to you to troubleshoot. Let’s look at how we can get to this point so we can understand which troubleshooting options are on the table.
What Causes the Flashing Question Mark?
Way back in the old days of Macs and PCs, there were no hard drives, which meant you had to keep your operating system on a floppy disk. The computer’s logic board was programmed to look for a floppy disk when powered on.
Today, people run computers with multiple internal and external hard drives, USB memory sticks, and DVD burners. Any of those disks could potentially hold an operating system that your computer can boot from, so in today’s world, the computer now has to ask, “Which disk do you want me to boot from?”
Because no one wants to have to tell the computer which disk every time the computer is turned on, the answer to “Which disk?” is stored in a little piece of the Mac’s memory called NVRAM (non-volatile random access memory).
When the Mac turns on, it first looks at the disk designated in NVRAM to see if there’s a valid operating system on it (a working version of Mac OS X). If it can’t find one, it will scan all the internal and external ports where you could have another disk, and if it finds a valid OS on one of those, it will boot from that disk.
If it can’t find anything to boot from, you get a flashing question mark.
So what can cause your computer to fail to find a good operating system? There are a number of possibilities. Here are the most common ones:
- Corrupt NVRAM that needs to be reset.
- A hard drive with a corrupt operating system or corrupt directory structure.
- A hard drive with no operating system.
- A hard drive that no longer functions.
- A working hard drive that the computer can no longer see because of bad cables or boards inside the computer.
Troubleshooting the Problem
Now that we know what causes the flashing question mark, let’s try to fix the problem. I’m going to troubleshoot from the tip to the bottom of my list above, as this order goes from the least to the most difficult.
- Hold down the option key and then turn on your computer while still holding it down. Soon, you should be presented with a blue screen.
- Over the next 1-2 minutes, your computer will search for disks it can boot from and put each bootable disk into its own little “square.”
- If you see the name of your hard drive (likely “Macintosh HD” unless you’ve changed it), click the icon and then the right arrow to boot from the drive. That should be all you need to do.
- If the drive doesn’t show up or does but fails to load, continue on…
No operating system/corrupt operating system/corrupt directory structure:
- At this point, we are going to need to boot either from the restore DVD (disc #1) that came with your computer, or (if you have upgraded the operating system separately) a Mac OS X install DVD. To boot from the disc, pop it into the DVD drive. While the computer should start booting from the disc shortly, you can also turn your computer off and back on while holding down the “c” key. This tells the computer to boot from the CD/DVD.
- If you’ve never booted from this DVD before, you should know that it can take multiple minutes to start up. You’ll likely have to select which language you want to use before you get to the installer screen.
- Once you get to the installer screen, you don’t want to install anything at this time. Instead, look up at the menu options, and one should be labeled, “Utilities.” Under Utilities, there is an option for “Disk Utility.” Choose Disk Utility, and that application should then open.
- Here’s a picture of what you should see in Disk Utility:
- We need to focus on a few things here. The first is what I have circled. This is the icon for my internal hard drive. Since most of you are trying to start up from your internal hard drive, it should be listed first and have the hard drive icon. You can see the icon below it is a CD, which represents my DVD burner (which would have the restore disc in it). If your left pane DOES NOT have a hard drive icon in it anywhere, you should skip down to the “Final Steps” section of this article.
- Notice that my hard drive has a top line that says “465.8 GB WDC WD5000…” The second line says “Macintosh HD.” Obviously, the second line is what I named my hard drive (which happens to be the default name). The first line is the name of the full disk itself, which basically says it is a 465 GB drive, made by Western Digital Corp. (WDC) and is a model WD5000… .
- Does any of this really matter? Well, if you have partitioned your hard drive (meaning it has more than one name — such as Macintosh HD and Boot Camp), you are concerned with the portion that has your operating system on it.
- The safest thing to do is click on the top line of the hard drive.
- Then click the “First Aid” tab (which is probably already selected).
- Next, we want to do two things: run “Repair Disk Permissions” and then “Repair Disk” (#1 and #2).
- These will check to see if files have bad permissions (which could cause the system to fail to boot), or if the directory structure of the disk is corrupt (which will prevent the computer from reading files on the disk).
- You should be prepared for this to take a long time (more than 15 minutes for the file permissions and anywhere from 5-60 minutes for the repair of the disk). Feel free to read the status of the task as it is being spit out. Don’t worry so much about the files that have bad permissions: there are almost always a few on every disk. Once the file permissions have been repaired, click on the “Repair Disk” button.
- Do mind the results of the repair disk. If there are problems, they will be highlighted in red. Disk Utility will try to repair the problems. If it does so successfully, it will actually tell you that the disk has been repaired successfully. If it cannot, it will tell you the disk cannot be repaired, again in red. If there are no problems, it will tell you the disk is OK in green.
- What do we do now that Disk Utility is done with its repairs? If Disk Utility found no errors or was able to correct the errors, we’ll quit Disk Utility from its menu. This will take us back to the installer. If it could not fix the errors, skip down to “Final Steps.”
- From the installer, again open the Utilities menu, and choose “Startup Disk.” Startup Disk will scan all the drives connected to your machine to see if it can start up from any of them. It will show you folders of the operating system from each disk it can start from. If it finds one, you can select it and choose to restart. Hopefully, your machine will boot back up, and you’ll be done.
- If it finds no valid systems (or if it does but your computer still will not boot), you have a decision to make: your problem could be that your existing operating system is corrupt and needs to be reinstalled OR your hard drive format is corrupt and needs to be erased OR your hard drive is bad.
- How do you resolve this? Well, we can reinstall the operating system. Quit Startup Disk and go back to the installer. From there, click Continue. Then, you will be presented with a screen that shows disks you can install onto. If you don’t see any, go down to “Final Steps.” If you see your hard drive, click it once.
- After you click it, you could be presented with a green sign or a red sign. The green sign means the operating system is ready to be installed. If you see that, this means your computer really does not recognize a valid operating system on your disk. You can choose to install the operating system, and your computer may start up, but you may lose any or all of your data by installing. You might consider taking your computer to an Apple Store if you want more technical advice.
- If you get a red sign, your computer will tell you why it can’t install the operating system. This may be because you have a newer operating system installed (like if you have 10.5.5 installed but your restore disc only has 10.5.0), or that you cannot install the operating system on your disk.
- What to do? Well, with your hard drive still selected, choose the “Options” button in the lower left-hand corner of the box. Here, you’ll be presented with three options: upgrade, archive & install, erase & install. Upgrade will be grayed out, so this is not an option. Archive and install means that the computer will attempt to move your old operating system to a safe place on the hard drive, install a fresh operating system that works, and keep your data intact. It is still possible to lose data with this option. Finally, there is the erase and install, which means exactly that: erase everything and reinstall the operating system. If you erase your drive, you WILL lose all of your data.
- Obviously, most people want to keep their data, so they’ll try the archive and install. If this doesn’t work, an erase and install may be necessary. You can try an archive first, and if that is unsuccessful, you can reboot from the DVD and do the erase and install. If neither is successful, go to “Final Steps.” I can’t emphasize enough that while these installs normally go smoothly, they can further damage the data on your drive (if there is more corruption than the installer and Disk Utility can see), so if you are apprehensive about pursuing this line of troubleshooting, you’re better off taking your machine to the Apple Store.
- If Disk Utility recognized your hard drive but could not successfully fix it or reinstall the operating system, the best answer is that you should take your computer to the Apple Store. The more detailed answer is that it is still unclear whether the problem is software or hardware. For the most part, you can eliminate software as the culprit if you are willing to erase your hard drive and reinstall the operating system (as outlined above). If it still doesn’t work, the culprit could be your hard drive, its cable, your RAM, or your logic board.
- If you’re not willing to erase your hard drive, you could purchase Alsoft’s DiskWarrior program. If this software cannot fix a corrupted disk, you probably will not find anything that can, and you will have to erase the hard drive (if software is the culprit).
- If your hard drive is not recognized by the computer, chances are that the hard drive is dead and will need to be replaced. It could also be the hard drive cable, RAM, or logic board in your computer, but those are less common culprits. Again, since you likely need a repair, you can take your machine into the Apple Store.
- There is one last piece of software you can run, and this can help determine if there is a problem with your hardware. The software is called the Apple Hardware Test, and it is located on the first restore disc that came with your computer (but not a retail Mac OS X install disc). To run this test:
- Put the restore disc #1 into your computer.
- Turn the computer on while holding down the “option” key on your keyboard to get that blue disk selector screen.
- Wait for all the disks to load, then select “Apple Hardware Test.”
- When the application loads, select “Extended Test” from the two button choices. The battery of tests will run. This could take anywhere from 15 minutes to 2 hours (nearly all of this time will be used to check your RAM).
IF the Apple Hardware Test gives you a hardware error message, this is proof-positive that there is a hardware problem. Write down the error message (listed in red) and take your machine to the Apple Store. If the test completes without any hardware error, this may mean that there is no hardware problem, but it may also mean the test simply cannot recognize the hardware problem. Thus, this test can only provide positive guarantees, not negative guarantees.
You may be disappointed to read that many of the solutions presented here require you to take your computer into the Apple Store. The reason for this is that a flashing question mark, in the end, usually does indicate your computer has a hardware problem. Trying to repair the disk directory or reinstalling the operating system, unless you have more knowledge or resources, is generally the most an end-user can do to troubleshoot this problem.
My last piece of advice, and please do not think this is intended to pour salt into the wound, is that you need to have a backup strategy. Hard drives don’t go bad because you did something wrong. They go bad because mechanical parts eventually break. Please back up your data so you do not lose your most prized photos, music, and data.
Have you tried these steps before? Do you have advice on the flashing question mark? What are some other solutions? Let everyone know in the comments.