Troubleshooting Mac OS X installation from CD or DVD

Starting up from the disc

Usually, you can start from the disc by putting it in your computer, restarting, and holding the C key. Or, put it in the computer and click the Install or Restore icon you see in the disc's main window (after which the computer will start from the disc without you needing to hold C.)

Mac OS X 10.4 tip: If your computer ejects the Mac OS X 10.4 Tiger Install DVD, your Mac probably doesn't have an Apple internal DVD drive or Apple SuperDrive, in which case you'll need Mac OS X 10.4 Install CDs. (If it does have an Apple DVD-ROM drive yet still ejects the disc, see this document.) If you need Mac OS X 10.4 Install CDs, check out the Mac OS X Upgrade website.

Troubleshooting tip: If the computer doesn't start from the disc—you never see the option to choose a language, for example—then see this document for troubleshooting tips.

Computer check

The Mac OS X Installer makes sure your computer can use the version of Mac OS X you're trying to install.

Troubleshooting tip: If you see a message that you cannot install Mac OS X on this computer, even though it should work with Mac OS X, you may need to install a firmware update. Restart your computer from the hard drive and install the latest firmware available for your computer.

Source disc check

During this helpful step, Installer takes a few moments to check the source disc itself before starting the installation process. If you see a message about a "failed checksum," then there may be an issue with your optical disc or optical drive (see the tips below).

Note: During this step, you may see a "Skip" button in the Installer window. If you haven't used your Install disc before (or recently), you should not skip this step.

Troubleshooting tips

1. Is that disc clean? Make sure the disc is clean and without significant smudges or deep scratches. If your disc is unusable, call AppleCare support for assistance.
2. Is this this original optical drive? If you have issues, make sure you're using the original Apple optical drive that was included with your computer (CD-ROM, DVD-ROM, DVD-RAM, CD-RW, Combo drive or Super Drive). This is only a concern in three scenarios: if you have replaced your original Apple drive with a non-Apple drive, if you have added a non-Apple drive to the second bay of a Power Mac G4 model with two drive bays, or if you are attempting to install from an external drive.
3. Will the disc's data copy to hard disk? If your computer will start up from any existing version of Mac OS, try copying the contents of the installation disc to your hard disk (if you have enough space). The ability to copy (but not install) the data is a simple test of the disc and of the hardware. If you encounter repeated errors, the hard disk or the disc may be unusable.
4. Can you isolate the issue to a single computer? If you have access to a computer with a spare hard disk or partition that can be erased, then you may test the installation disc on it to verify that the disc is good. After the test is complete, the test disk or partition should be erased if you are only licensed to install the software on one computer.

Destination disk check

Before the actual installation begins, the installer checks the selected volume to ensure the integrity of the disk. If the disk check finds issues that it cannot repair, the installation will not start.

You must resolve such hard disk issues before you can install. If you have a third-party disk utility that's compatible with your version of Mac OS X, you can try that. If no utility can correct the issue, you must back up your important files, then perform an erase install.

Mac OS X 10.4 Tiger tip: See Only use Mac OS X 10.4-compatible disk utilities with Mac OS X 10.4 volumes.

Tip: You can also contact an Authorized Apple Service Provider (AASP) for assistance.

Installation starts but does not complete?

If you intentionally skipped the "Checking your installation DVD or CD" (Source disc check mentioned above) step at the beginning of the installation, you should allow the check to complete to make sure the installation media is OK.

If you see a message such as one of these, use the tips below:

• "There were problems installing the software"
• "There were errors during the installation...Please try again."
• "Because of a problem, installing Mac OS X could not be completed."
• "Installer could not validate contents of the [PackageName] package" (where '[PackageName]' is the name of one of the packages on the installation disc).

Tip: RAM issues may cause an installation issue such as this. Try removing any third-party RAM that's been installed. Remember to make sure you have at least 128 MB (Mac OS X 10.3 or earlier), 256 MB (Mac OS X 10.4), or 512 MB (Mac OS X 10.5 Leopard or later) of memory installed.

You can also retry the installation on the same computer, or try a different compatible computer (as a test) to determine whether the issue is isolated to the Mac OS X disc or to the computer itself.

Did the installation finish?

If the installation of Mac OS X finishes and the computer restarts, it is highly unlikely that anything is wrong with your disc or that Mac OS X was "installed incorrectly." If you have issues that aren't related to installation, this document can help.

It's OK if reinstallation is slower

Installing Mac OS X on a disk that already has Mac OS X is slower than installing on a disk that has no Mac OS X installed. That's OK because of the file comparison that happens during a reinstall takes a little time. See the note on "downgrade" installations here.