Blue Screen on OSX Leopard Upgrade

For those of you — like me — who experienced a blue screen upon booting an upgrade install of Mac OS X Leopard, here are a few tips to clear the errors that are preventing the system from rebooting.

COMMAND LINE METHOD
Reboot your Mac while holding Cmnd-S on your keyboard. Your computer will boot into the single user mode, no graphics, only the good old command line.

To modify files you need to type the following

/sbin/fsck -fy (then press return)
/sbin/mount -uw / (then press return again)

You can either go straight to their respective folders to delete these four files, or you can do it in one go by typing the following commands and pressing return on your keyboard after each line:

rm -rf /Library/Preference Panes/Application Enhancer.prefpane
rm -rf /Library/Frameworks/ApplicationEnhancer.framework
rm -rf /System/Library/SystemConfiguration/ApplicationEnhancer.bundle
rm -rf /Library/Preferences/com.unsanity.ape.plist

Reboot Leopard – blue screen may appear for several minutes during system check.
Suggested – reboot your Mac from the installation DVD, open Disk Utility and repair the permissions.

My preferred way to handle deleting files is to stay within the OS and avoid the command line altogether.

SECOND MAC FIREWIRE METHOD
Another alternative (which is easier – in my opinion – if you own a second Mac) is to boot the Leopard upgrade into Firewire mode.
Connect your Leopard install to second Mac via Firewire.
Reboot Leopard install holding down “T” at boot to initiate Firewire mode.
Using second Mac, launch finder and browse Leopard install to delete files.

/Library/Preference Panes/Application Enhancer.prefpane
/Library/Frameworks/ApplicationEnhancer.framework
/System/Library/SystemConfiguration/ApplicationEnhancer.bundle
/Library/Preferences/com.unsanity.ape.plist

Unmount Leopard upgrade in second Mac’s Finder.
Disconnect Firewire
Reboot Leopard – blue screen may appear for several minutes during system check.
Suggested – reboot your Mac from the installation DVD, open Disk Utility and repair the permissions.

Many (most?) Mac users are not reporting any problems in upgrading from Tiger to Leopard. The root cause of the blue screen is the unsanity app enhancer, which is a common (yet unsupported) third-party resource app.

For those who have not yet installed Leopard, the Unsanity APE app provides an uninstaller that can be used first to remove the framework before the new operating system is installed. Alternatively, users can use the “archive and install” option, which places a new copy of Leopard on the user’s computer while moving older operating system files to another folder. That would have the effect of moving the potentially offending APE software to a location where it can do little to interfere with the installation process

To uninstall Application Enhancer – open your System Preferences and in the “Other” section will be the icon for Application Enhancer (If you have it installed), click it and then click the “Troubleshooting” tab, next click the “Uninstall Applications Enhancer” tab.

Given the sheer number of “power users” who have this A.P.E. installed either with or without their knowledge, I find it *very* hard to believe that Apple didn’t experience more than their fair share of blue screen boots during beta testing.

Long story short, while it’s not Apple’s fault, per se, they certainly had an opportunity to modify the Leopard upgrade installation and (apparently) chose not to.