Although Kernel Panic doesn’t sound very reassuring if you know what it is and how to handle it, there’s a good chance your Mac will emerge unharmed.
Kernel Panic (KP) is the equivalent of the Windows Blue Screen of Death for Unix-based operating systems, such as OS X and Linux.
Technically, Kernel Panic is a kind of emergency procedure that the operating system enables when it comes across a system error from which it cannot safely recover. Specifically, the OS will shut down automatically, and to use the computer again you’ll have to restart it manually.
Kernel Panic is very rare, and isn’t necessarily a symptom of a major problem. It can also be caused, for example, by a malfunction of a defective data package.
So, our first tip: if you only get one KP and, after the reboot, it doesn’t happen again (or at least it doesn’t happen again for a long time) and everything seems to work normally, then you can relax and ignore what happened.
If the Kernel Panic starts to become more frequent (for example, a couple every month), you should identify the problem and fix it.
In this article, we’ll tackle the problem from a software point of view, but remember that sometimes the KP could have been caused by hardware.
What can cause Kernel Panic?
The most common cause is a hardware failure – either the Mac itself, or an external device or application. Some of these problems are only temporary and will disappear after a reboot, as we have already mentioned. Others are more complicated, and will stop you using your computer.
Badly-written drivers or plugins could cause a KP or even the random presence of specific conditions. In these cases, the Mac should work properly again after the reboot.
There are other, more complex problems that need to be identified and fixed. Let’s start with the ones that are easier to spot.
How to recognize Kernel Panic
The easiest symptom to recognize is the classic screen with the start button image in the background, and the multilingual message that tells you: “You need to restart your computer.”
Sometimes, however, you don’t get this default message, and your Mac could spontaneously restart, turn off, or stop responding to commands, forcing you to shut down the computer forcibly.
In these cases, to be certain that it was a Kernel Panic, just go to /Library/Logs/DiagnosticReports (in Mavericks). There, if the problem was really a KP, you’ll find a log with the details of the incident .
Sometimes, however, this file could be missing, even if it was a Kernel Panic. In this case (even though it’s hard to tell), the problem is probably in your Mac’s hardware, such as a faulty RAM or hard drive.
We’ll see later how to deal with the problem if that’s the case.
When applications fail
Sometimes a badly-written program could be behind a Kernel Panic.
OS X 10.8 onwards, after a reboot your Mac will automatically give you the choice to open the programs that you were using just before the KP.
The best thing to do is to say yes, clicking on Open. If one of the applications is the cause of the Kernel Panic, it will occur again. If the computer crashes again, now you know you shouldn’t open those applications in the second reboot.
Instead, reopen the applications one by one until you find the one that’s behind the KP. Uninstall it and the problem should be resolved.
Keep your system updated
By keeping your OS, programs and firmware up-to-date , you’ll decrease the likelihood of conflict and therefore of a Kernel Panic.
- Open Software Updates in the Apple > Update menu and update all programs (operating system, firmware and software downloaded the Mac App Store).
- Check that the versions of the programs you downloaded from the store are the most recent. You can, for example, check the Mac section on Softonic, or use the built-in function in the applications, if they have one.
Sometimes it’s a startup issue
To check if startup items are responsible for the Kernel Panic, follow these steps:
- Disable all the login items (System Preferences> Users and Groups, then select your user, go to the Login Items tab, select all the items and click on the ‘minus’ sign)
- Restart your Mac in Safe Boot Mode (hold down the Shift key during startup).
- Now you need to disable all login items for all accounts and groups, using the same method described above.
- Some applications install items that start automatically with the operating system, before you even log in. You must also disable those. To do this, go to Library/StartupItems.
There you’ll find folders with the names of applications. Select them all and drag them into any other folder (you’ll need the administrator password). When the Kernel Panic problem is solved you can put them back into the same folder.
- Now you can restart your Mac. If there’s no Kernel Panic this time, then one of the login or startup items was responsible for it. Put the items back into the folder one by one, restarting the computer each time, until you find the cause.
Find the drivers that your Mac doesn’t like
If you recently installed drivers, for example for a new printer, and as soon as you tried to use it you got a Kernel Panic, it could be the printer’s fault: incorrect drivers can make your OS crash.
Check carefully that you have the latest drivers for that specific device (and not a similar model), and that they are compatible with your OS X version. If you don’t know what version you are using, go to the Apple menu in the upper left corner and click on About This Mac.
Kernel Panic can also be caused by the hardware itself, which for some reason your Mac doesn’t like. If you’re sure that the installed drivers are the right ones, and every time you turn on the device your system crashes, the only solution is to stop using it.
Get your hard disk in shape
The hard disk must have free space and be in good condition. To do this, get rid of things you don’t need or use. We all have files that are no longer useful or applications we never use. You can use OmniDiskSweeper, which creates an index of all the contents on your Mac and sorts them according to their size.
This will help you find files that are heavy but useless, and could free up space equal to about 5 times the amount of RAM installed, giving your computer a little room to breathe.
Something else you can do is a little hard disk maintenance. To do so, start the Mac from the OS installation disk (insert the DVD into the drive and restart your Mac while holding the C key) or the recovery partition for OS Lion (restart while holding down Command and R).
Now run Disk Utility Applications > Utilities > Disk Utility, select the HD in the left column and just click on Repair Disk.
Nothing works? Reinstall OS X
If you’ve tried everything and nothing seems to work, try reinstalling the operating system. If you have OS X 10.9 Mavericks, this is the procedure according to Apple:
- Make sure your power adapter is plugged in
- Restart your Mac holding down the Command and R keys
- Choose a network from the Wi-Fi menu or connect an Ethernet cable
- Select Disk Utility, then click Continue
- Select your startup disk on the left, then click the Erase tab
- Choose Mac OS Extended the Format menu, enter a name, then click Erase
- After the disk is erased, choose Disk Utility > Quit Disk Utility
- Select Reinstall OS X, click Continue, then follow the onscreen instructions
Relinquish control, and just bring it back to the store
Now that we have explored even the most unpleasant of the possible consequences of a Kernel Panic, the initial message is worth repeating: this is a very rare problem, and can be fixed in almost every case.
OS X is a Unix-based operating system, an OS backed by 45 years of development (the first release was in 1969!), that is why it has a very solid architecture and these problems are rare.
And if you’re a thorough Mac user, and use Time Machine as a backup, even in the worst case scenario you’ll be able to recover most of your digital data.
One last piece of advice: Kernel Panic can also be caused by internal hardware components (such as RAM or HD). If you believe that’s the case because, for example, the problem started after replacing the original hard drive or after adding memory to your computer, we recommend you take it to an Apple Store.
If you’re new to the Mac world, check out our Moving to Mac Guide.
