I Have mac osx 10.5.8 and have tried to update to mac osx snow leopard 10.6.3, but I constantly get the install failed message. What could be the problem?

Question

My imac is currently running mac os x 10.5.8. I've tried to install mac osx snow leopard 10.6.3, but have been unsuccesful because the disc fails to install.
What could be the problem?

Answer 1

noondaywitch wrote:
You should boot from the Installer DVD by holding down the C key during start up until the Apple logo and spinning cog wheel appears. Allow plenty of time for the installer to appear - it can take several minutes when booting from a disc.
I suggest not doing this unless the Apple recommended method (starting by double-clicking on the
Install Mac OS X icon while booted up normally) fails.
There are several reasons for this:
The Apple method performs a check of the DVD's integrity before starting up from it. This can't be done if you start up directly from the DVD.
The Apple method "phones home" using the current OS's network settings to check for updates to the incompatible items database included on the DVD & writes a lot of pre-install data (the 'Mac OS X Install Data' stuff) to the HD before restarting automatically from the DVD to finish the installation. This may not work as expected if you start up directly from the DVD.
The pre-install data on the HD speeds up the installation process (because running the OS from the HD to build the data is faster than doing that while running from a DVD).
The Apple method makes it possible to "gracefully" cancel the installation before the automatic restart occurs without leaving the existing OS on the HD in a corrupted, "half-installed" state unable to restart the Mac. This sometimes happens if the installation process hangs & one has to force-restart the Mac to recover. As long as this occurs during the "pre-install phase" before the restart, the existing OS should remain untouched & intact.
Also note that the Snow Leopard installer is quite a bit more sophisticated than the previous ones like for Leopard or Tiger. It automatically performs the equivalent of Disk Utility's Verify Disk step before beginning the installation & performs more checks during the installation process (including checking the pre-install data for errors). It is usually not necessary to remove the "Mac OS X Install Data" folder after a failed installation, which may just cause the process to take longer on subsequent attempts, but if nothing else helps it is certainly something worth trying.