Firmware updates for Intel-based Macs require a GUID partition scheme

  • Last Modified: July 24, 2008
  • Article: HT2434
  • Old Article: 303609

Summary

Firmware updates will not install on an Intel-based Mac if the computer is using a non-standard partition scheme, such as an fdisk scheme. You may see an "unexpected error occurred (0); unable to upgrade firmware" error message, or your computer may start normally (after a single beep if the power button is held) when attempting to install the firmware update.

Products Affected

Mac Pro, Mac mini (Mid 2007), Mac mini (Late 2006), Mac mini (Early 2006), iMac (20-inch, Mid 2007), iMac (24-inch Mid 2007), iMac (Mid 2006 17-inch), iMac (Early 2006 20-inch), iMac (Early 2006 17-inch), iMac (24-inch, Late 2006), MacBook Pro, MacBook, iMac (20-inch Late 2006), iMac (17-inch, Late 2006 CD), iMac (17-inch, Late 2006), MacBook Air

Discovering the partition scheme

You can easily find out what partition scheme a disk has using Disk Utility.

  1. Open Disk Utility:

    • If you're started from a Mac OS X installation disc, choose Disk Utility from the Utilities menu.
    • If you're started from your computer's Mac OS X volume, open Disk Utility from the Utilities folder. You can get there by choosing Utilities from the Finder's Go menu.
  2. Select the hard disk (not the volume) in the left side of the Disk Utility window. The disk usually contains the name of the drive vendor, not "Macintosh HD" or a name you chose.

    Tip: In Disk Utility, volume names are indented on the left side of the window. Disk names are not indented.
  3. From the Disk Utility File menu, choose Get Info.
  4. Look for the "Partition Scheme:" line. An Intel-based Mac can only install firmware updates on a disk with the "GUID Partition Table."

Solution

If your partition scheme is not "GUID_partition_scheme," you have two options for installing the firmware update.

Option 1: Use an external startup disk

If you have a bootable external disk, such as a FireWire disk, that is configured with the correct partition scheme (GUID_partition_scheme), start up from it using Startup Disk preferences, then apply the firmware update during start up.

The firmware update is applied to your Mac, not your external disk.

Option 2: Backup data, erase and partition the disk, reinstall Mac OS X

This option will erase the disk and allow you to install the firmware update. Important: Back up your important data. Partitioning a hard disk erases all data on the disk.

  1. Back up your important data. Partitioning a hard disk erases all data on the disk.
  2. Start from your Mac OS X installation disc, then choose Disk Utility from the Utilities menu.
  3. Select your computer's hard disk.
  4. Click the Partition tab in the Disk Utility window. If the partition tab is not visible, make sure you've selected the disk (not volume) in the left side of the window.

    Tip: In Disk Utility, volume names are indented on the left side of the window. Disk names are not indented.
  5. Choose the desired number of partitions from the Volume Scheme pop-up menu. It's OK to choose "1 Partition" if you only want one.
  6. Click Options.

    Note: On some Intel-based Macs, the Options button does not appear under the partition tab. Use the erase tab to erase the disk instead. This will change the partition scheme to the default "GUID Partition Scheme". You can then use the partition tab to create additional partitions if desired.

  7. From the Partition Scheme pop-up menu, choose "GUID Partition Scheme".
  8. Click OK.
  9. Make any other changes you wish in the Volume Information section, such as partition size or naming.
  10. Click the Partition button to erase and partition your disk.
  11. When partitioning finishes, reinstall Mac OS X on the volume.
  12. After reinstalling Mac OS X, download and install the firmware update for your computer. Afterwards, you can restore your backed-up data.
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