Computers, Laptops & Tablets Apple How to Fix a Mac That Stalls on Gray Screen at Startup Troubleshooting Mac startup problems By Tom Nelson Writer Tom Nelson is an engineer, programmer, network manager, and computer network and systems designer who has written for Other World Computing,and others. our editorial process Facebook Twitter Tom Nelson Updated November 09, 2019 Apple Macs iPad Tweet Share Email Mac startup problems 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. This startup issue is called the gray screen problem because historically, the display would turn gray during the start-up phase when the problem struck. The more recent Retina Mac models have a black or very dark display instead. Nusha Asjaee ©Lifewire The gray screen problem occurs after a Mac is started or restarted. The problem is characterized by the display changing from the blue screen that occurs at power up to a gray screen, though you might not see the blue screen because it tends to go by very fast. It's also possible that your specific Mac model doesn't display the blue screen. Apple has streamlined the startup process, and fewer screens types display during startup. You might see only the gray screen. 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. There are no unusual noises, such as disk access, optical drive spin up or down, or excessive fan noise; just a Mac that won't continue to the login screen or the desktop. Another startup problem that's mistaken for the gray screen issue is a gray screen with a folder icon and a flashing question mark. That's a separate problem, which is easy to fix with the help of our troubleshooting guide. How to Fix the Gray Startup Screen on Mac Disconnect all external peripherals, and keep them removed for the duration of these steps unless otherwise noted. Turn off your Mac by pressing and holding the power button to force it down.If applicable, remove the Ethernet cable, audio in/out cables, headphones, and any other peripherals.Power your Mac back on. Don't disconnect the keyboard, mouse, or display. If your keyboard or mouse is connected through a USB hub, bypass the hub by plugging the keyboard and mouse directly into your Mac for these tests. 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 it 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. If your Mac starts back up without issue, then you'll know that it's a problem with a peripheral. You'll 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. Getty Images Swap your mouse and keyboard with a known good pair, and then restart your Mac. If you don't have spares, just disconnect them and restart 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 to confirm. Start your Mac using the Safe Boot process if no peripheral or cable appears to be at fault. To do that, first disconnect all of the peripherals, except the mouse and keyboard. During the Safe Boot, your Mac performs a directory check of your startup drive. If the drive directory is intact, the OS continues 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 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. Reset PRAM and reset SMC 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. Resetting the PRAM and the SMC returns your Mac's hardware to its default settings. For instance, sound levels are set to the default, the internal speakers are set as the source of audio output, and the display options and brightness reset. Start your Mac back up after resetting the PRAM and SMC. If it comes on normally, reattach your peripherals one at a time, restarting the Mac after each, to verify that none of them caused the original gray screen issue. 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, and you'll need to replace it. However, you should be able to continue working with your Mac until you get the replacement RAM. Unfortunately, we're getting to the point where the troubleshooting steps will likely cause you to lose some, if not all, of the data on your startup drive. So, before we go there, be sure to try this RAM fix first. Repair the startup drive by booting to external media, like an install disk. This verifies if the startup drive is having problems. Tony Webster/Wikimedia/CC by 2.0 Start from an OS X or macOS install disk: Insert the installer DVD into your Mac's optical drive.Shut down your Mac.Start your Mac while holding down the C key. This tells your Mac to boot from the media in the optical drive. Start from the Recovery HD: Shut down your Mac.Start your Mac by pressing Command+R. Start from another startup drive, like an external HDD or a flash drive that contains a bootable OS: Shut down your Mac.Connect the external drive or plug the flash drive into a USB port.Start your Mac by holding down the Option key.A list of available drives that have a bootable OS X or macOS system installed displays.Use the arrow keys on your keyboard to select the target drive, and then press Return or Enter. If your Mac boots using any of these methods, repair the startup drive using instructions in the Disk Utility First Aid guide (OS X Yosemite and earlier) or with Disk Utility's First Aid (OS X El Capitan or later). If you started from an install DVD or the Recovery HD, 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). If at this point you successfully started your Mac but the repair process didn't work, the startup drive may need to be replaced, which involves reinstalling the entire operating system. If you can't repair your startup drive using Disk Utility, try a third-party drive utility. If you do repair the startup drive, it may need to be replaced in the near future. Boot into single-user mode to repair the 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. The display looks like an old-fashioned terminal from the days of mainframes and time-share computing systems, but it's 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 launching the basic OS kernel. Remove or replace the startup drive, or take your Mac to an authorized service center, such as the Genius Bar at an Apple store. 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's preventing your Mac from booting.