Troubleshoot Upgrade Problems

Even if you diligently followed all the instructions in this book, you might encounter problems while upgrading. I can’t anticipate every difficulty you may have (or provide solutions in every case), but here are some of the most likely issues and how to deal with them.

Can’t Run the Sierra Installer…

If the Sierra installer icon has a slash through it, or if you try to run it and it quits immediately, the three likely causes are:

  • You’re trying to run it on a Mac whose CPU is incompatible with Sierra (see Model Support for full details). Solution: Buy a new Mac. (Sorry.)
  • The installer didn’t fully download, or the file was damaged. Solution: First delete the installer. Then open the App Store app, click Purchased, and download Sierra again.

Can’t Select Installation Volume…

If you run the Sierra installer, click Show All Disks when asked to choose a destination, and find that the volume on which you want to install Sierra isn’t available, chances are excellent that if you click the volume in question, the installer will tell you why it can’t be used—for example, not enough disk space, wrong partition map scheme, or wrong format—and, at the same time, tell you how to fix that problem.

You may also see a message about an “unsupported partition structure,” which means the installer thinks the disk containing the volume where you want to put Sierra isn’t partitioned in one of the officially sanctioned ways. Repartitioning your disk as described in Prepare Your External Drive is the only reliable solution.

Come to mention it, repartitioning is, in fact, the best (if brute-force) way to eliminate almost every possible cause of an unselectable volume. If all else fails, try that.

Mac Won’t Start Up under Sierra…

Following installation—either on the first restart or a subsequent restart—if your machine will not start up under Sierra (or if you experience a kernel panic upon the first restart), try these steps in order until you are able to start up normally:

  1. Disconnect non-essential USB devices: USB devices have been known to interfere with the Mac startup sequence, so if your Mac gets stuck on a gray screen and won’t finish booting, try this:
    1. Press and hold the power button for about 10 seconds until your Mac shuts down.
    2. Disconnect all USB cables from your Mac except any that go to a keyboard, mouse, or other pointing device.
    3. Press the power button again and wait for your Mac to start. If it starts normally, you can then reconnect your USB devices. If it’s still stuck after 10 minutes or so—or if it starts but then you experience a kernel panic—move on to the next step.
  2. Try a Safe Boot: Restart your Mac. (If the Mac is frozen or you see a kernel panic message, press and hold the power button for about 10 seconds until the Mac shuts down. Then press the power button to turn it back on.) As soon as you hear the startup chime, press Shift. Release the key when the gray Apple logo appears on the screen. The Mac will complete the startup process, which may take considerably longer than usual. You’ll eventually see the words “Safe Boot” on the screen—likely in red at the top of the login screen.

    If Sierra starts up normally after a Safe Boot, a third-party extension or startup item may be the culprit. Check in /System/Library/Extensions, Library/StartupItems, /System/Library/StartupItems, /Library/LaunchAgents, /Library/LaunchDaemons, and ~/Library/LaunchAgents for third-party items that haven’t been updated recently (older items are more likely to have compatibility problems). This may include drivers for audio interfaces and input devices, security software, and certain system enhancements.

    If you find any that you explicitly recognize and suspect as a culprit, look for an uninstaller from the developer, and if there is one, use it. If not, consult the documentation that came with the software, or the developer’s Web site, for removal instructions. (I recommend against manually dragging these items to the Trash unless you can find no other way to remove them.)

    Restart and see if the problem is still gone. If so, reinstall the programs that use the deleted items one at a time, restarting after each one, until you find the culprit.

    If the problem does not go away after a Safe Boot, go to…

  3. Try macOS Recovery: Assuming the Sierra installer succeeded in installing the Recovery HD volume (or that your Mac already had one from a previous installation of OS X), you can boot into macOS Recovery by choosing Apple  > Restart, clicking Restart, and immediately holding down Command-R until the gray Apple logo appears. A few moments later, you’ll see an macOS Utilities window that tells you you’re using macOS Recovery (more about this in a moment).

    Once in macOS Recovery, select Disk Utility and click Continue. When it opens, click First Aid and follow the prompts to repair any problems that may have appeared on your Sierra volume. Choose Disk Utility > Quit Disk Utility to return to the macOS Utilities window. Then choose Apple  > Restart.

  4. Try another startup volume: If you need to run Disk Utility but macOS Recovery isn’t available, try:
    • A bootable duplicate: The easiest option is to restart from your bootable duplicate (attach the drive, hold down the Option key when restarting, select the duplicate, and press Return), and then run Disk Utility.
    • Apple-supplied boot media: Boot from a Snow Leopard Install DVD (if your Mac came with one). Then choose Utilities > Disk Utility.
    • Target Disk Mode: If your Mac and another Mac you have access to (that can definitely start up correctly) both have FireWire or Thunderbolt ports, connect the two with a FireWire or Thunderbolt cable. Restart the good Mac, holding down the T key to turn it into a fancy external drive. Then restart the misbehaving Mac, holding down the Option key, and select the good Mac’s startup disk. Once you’ve booted, run Disk Utility from the good Mac to try to fix the boot disk of the misbehaving Mac.
  5. Remove any nonessential hardware: Try restarting with only your Apple-supplied keyboard, mouse, and display attached, and without any third-party PCI or video cards. You may even need to remove extra RAM. If this works, check for driver updates, and then reattach the devices one at a time, restarting after each one.
  6. Reinstall Sierra: If you still can’t start your Mac, consider reinstalling Sierra. Perform a clean install (described in Upgrade Using Plan B: Clean Install), omitting items in the Applications category when you work your way through the file transfer portion of the installation to eliminate any possibility of software conflicts. (You can add those items later using Migration Assistant.)

In most cases, these steps will lead to a happy Sierra installation.

Finder Crashes or Hangs…

Even if you diligently update all your software before installing Sierra, you could run into a third-party app that has problems and yet isn’t disabled by Setup Assistant. One symptom to look for is the Finder repeatedly crashing—that is, your Finder windows and Desktop icons keep appearing and disappearing. Another is a Finder hang—even after several minutes, the Finder doesn’t respond to commands such as Finder > Empty Trash or File > New Finder Window.

If you suspect that the Finder is crashing or hanging, open Console (in /Applications/Utilities), and watch the error messages as they flit by. If you see an app or filename repeatedly, that could be the source of the misbehavior. Try disabling it (if you know what and where it is), or follow the instructions in Mac Won’t Start Up under Sierra….

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