How to Fix a Mac That Stalls on Gray Screen at Startup

Troubleshooting Mac startup problems

Sad looking person looking at iMac
Don't look so forlorn, you can fix your Mac when it is stuck on the gray startup screen. uniquely india, Getty Images

Mac startup problems can take many forms, but stalling at the gray screen can be one of the most troublesome because there are so many possible causes. In addition, there are many Mac issues that get mistaken for the gray screen startup problem.

What is the Gray Screen Startup Problem?

It’s not always a gray screen, as strange as that may sound. The “gray screen” problem can also manifest itself as a black screen; actually, a screen so dark you may mistake the display as being powered off. This is especially true of Macs with built-in Retina displays, such as the Retina iMac models that don't have a power on indicator.

We call the startup issue the gray screen problem because historically, the display would turn gray during the startup phase when the problem struck. Nowadays, with the more recent Retina Mac models, you’re more likely to see just a black or very dark display instead. Even so, we'll continue to call this the gray screen problem, as that is the name that is most well known.

The gray screen problem can occur right after you start or restart your Mac. The problem is characterized by the display changing from the blue screen that occurs at power up to a gray screen. ​You may not see the blue screen as it tends to go by very fast. It is also possible that your specific Mac model does not display the blue screen. Apple has been streamlining the startup process, os the days of multiple screens types during startup are fading away.

You may see only the gray screen itself. It may also include the Apple logo, a spinning gear, a spinning globe, or a prohibitory sign (a circle with a slash drawn through it). In all cases, your Mac seems to be stuck at this point. There are no unusual noises, such as disk access, optical drive spin up or down, or excessive fan noise; just a Mac that seems stuck and won't continue to the login screen or the desktop.

There is another common startup problem that is often mistaken for the gray screen issue: a gray screen with a folder icon and a flashing question mark. That is a separate problem, which you can usually easily fix by following this guide: How to respond to a flashing question mark on a Mac.

Resolving the Gray Screen Issue on Your Mac

One of the most common problems that can cause the gray screen issue is a bad peripheral or peripheral cable. When a bad peripheral is plugged into your Mac, it can prevent your Mac from continuing the startup sequence, and cause it to stall while it waits for the peripheral to respond to a command. The most common form of this is when a bad peripheral or its cable causes one of the signaling pins on one of Mac's ports to get stuck in one condition (set high, set low, or shorted out to ground or positive voltage). Any of these conditions can cause your Mac to freeze during the startup process.

Disconnect All External Peripherals

  1. Start by turning your Mac off. You will need to press and hold your Mac's power button to force your Mac to shut down.

  2. Disconnect all of your Mac's peripherals, except the keyboard, mouse, and display. Be sure to disconnect any Ethernet cable, audio in or out cables, headphones, etc.

  3. If your keyboard or mouse is connected via a USB hub, be sure and bypass the hub by plugging your keyboard and mouse directly into your Mac for these tests.

  4. Start your Mac back up.

If your Mac starts back up without issue, then you'll know that it's a problem with a peripheral. You will need to shut your Mac back down, reconnect one peripheral, and then restart your Mac. Continue this process of reconnecting one peripheral at a time and then restarting your Mac until you find the bad peripheral. Remember that the problem can also be a bad cable, so if you plug a peripheral back in and it causes the gray screen issue, try the peripheral with a new cable before you replace the peripheral.

If you still have the gray screen issue after reconnecting all of your peripherals, the problem could be with the mouse or keyboard. If you have a spare mouse and keyboard, swap them with your current mouse and keyboard, and then restart your Mac. If you don't have a spare mouse and keyboard, disconnect your current mouse and keyboard and then restart your Mac by pressing and holding the power key.

If your Mac gets to the login screen or desktop, then you'll need to determine whether the problem is the mouse or the keyboard. Try plugging in one at a time and then restarting your Mac.

Peripherals Not at Fault

If no peripheral or cable appears to be at fault, there are still a few possible problems with your Mac that can cause the gray screen to occur.

  1. Disconnect all of the peripherals, except the mouse and keyboard.

  2. Start your Mac using the Safe Boot process.

During the Safe Boot, your Mac will perform a directory check of your startup drive. If the drive directory is intact, the OS will continue the startup process by loading only the minimum number of kernel extensions it needs to boot.

If your Mac successfully starts up in Safe Boot mode, try restarting your Mac again in normal mode. If your Mac starts and makes it to the login screen or the desktop, then you'll need to verify that your startup drive is working correctly. Chances are the drive has some issues that need to be repaired. You can use Disk Utility's First Aid tools to check and repair your drive; you may even need to replace the drive. Good thing you have a current backup, right?

If you're unable to start your Mac in Safe Boot mode, or your Mac starts in Safe Boot mode, but it won't start up normally, you can try the following:

Warning: Resetting the PRAM and the SMC will return your Mac's hardware to its default settings. For instance, sound levels will be set to the default; Mac's internal speakers will be set as the source of audio output; the date and time may be reset, and the display options and brightness will also be reset.

Once you reset the PRAM and SMC, try starting up your Mac. Peripherals other than the keyboard and mouse should still be disconnected.

If your Mac starts up normally, you will need to reattach your peripherals one at a time, restarting after each, to verify that none of them caused the original gray screen issue.

If Your Mac Still Has the Gray Screen Issue

Unfortunately, we're getting to the point where the possible methods of fixing the problem will likely cause you to lose some, if not all, of the data on your startup drive. But before we go there, try this one fix.

RAM Issues

Remove all but the minimum amount of RAM from your Mac. If you added any RAM to your Mac after you bought it, remove that RAM, and then see if your Mac starts normally. If it does, then one or more pieces of RAM have failed. You will need to replace the RAM, although you should be able to continue working with your Mac until you get the replacement RAM.

Drive Issues

With RAM as a possible culprit out of the way, it's time to concentrate on your Mac's startup drive.

The assumption at this point is that your Mac's startup drive is having problems that are keeping your Mac from successfully starting up. However, before we do anything drastic, we need to verify that your Mac can start from an OS X or macOS install disk, the Recovery HD, or another startup drive, such as an external hard drive or a USB Flash drive that contains a bootable OS. If so, then your startup drive is likely the problem.

Starting From an OS X Installer DVD

  1. Insert the installer DVD into your Mac's optical drive.

  2. Shut down your Mac.

  3. Start your Mac while holding down the c key. This tells your Mac to boot from the media in the optical drive.

Starting From the Recovery HD

  1. Shut down your Mac.

  2. Start your Mac by holding down the command + r keys.

Starting From an External or Other Bootable Drive

  1. Shut down your Mac. Connect the external drive or plug the flash drive into a USB port, if you haven't already.

  2. Start your Mac by holding down the option key.

  3. You will see a list of available drives that have a bootable OS X or macOS system installed. Use the arrow keys on your keyboard to select the target drive, and then press return or enter.

Using Single-User Mode to Repair a Startup Drive

One of the less well-known special startup modes that a Mac can operate in is known as single-user. This special startup mode boots the Mac to a screen that displays information about the startup process. To many, the display looks like an old-fashioned terminal from the days of mainframes and time-share computing systems. But it's actually more akin to the startup sequence in many Unix and Linux operating systems. In fact, many of the same commands are available from the prompt.

When in single-user mode, the Mac doesn't automatically load the GUI, including the Desktop; instead, it stops the boot process after loading the basic OS kernel.

At this point, you can use various commands to check and repair your Mac’s startup drive. You can find complete instructions for repairing a drive using single-user mode in the guide: How Can I Repair My Hard Drive If My Mac Won't Start?

If you are unable to start your Mac with any of the methods listed above, you may have a damaged startup drive or another internal component that is preventing your Mac from booting. You can try removing or replacing the startup drive, or you may wish to take your Mac to an authorized service center, such as the Genius Bar at an Apple Store.

If your Mac starts with one of the methods listed above, then you may be able to repair your startup drive.

Please note that your startup drive may have problems that can cause you to lose data during the repair process. If you do not have a current backup of your data, consider taking your Mac to an expert to attempt to recover data from your startup drive.

Start your Mac again by booting from the install DVD, the Recovery HD, or an external device. You can use Disk Utility to repair your drive. If you started your Mac from an external device, you can use the instructions in the Disk Utility First Aid guide (OS X Yosemite and earlier) or Repair Your Mac's Drives With Disk Utility's First Aid (OS X El Capitan or later) to repair your startup drive.

If you started from an install DVD or the Recovery HD, you will use the same basic steps, but the Disk Utility application won't be located in the Applications folder. Instead, you'll find it as a menu item in the Apple menu bar (if you started from the install DVD) or in the window of Mac OS X Utilities that opens (if you started from the Recovery HD).

After repairing your startup drive, check to see if you can start up your Mac normally. If you can, then reconnect your peripherals and try starting your Mac again. If everything is working correctly, you may need to start thinking about a replacement startup drive. Chances are the drive will have problems again, and sooner rather than later.

If you can't repair your startup drive using Disk Utility, you can try other third-party drive utilities, but even if you successfully get it running, chances are you will still need to replace the drive in the near future.

If you were not able to get the drive working at all, no matter what you tried, but you could successfully start your Mac from the installer DVD, the Recovery HD, or an external drive, then more than likely you will need to replace your startup drive. Once you replace the startup drive, you will need to install Mac's operating system.