Failure to boot after installing Leopard (Mac OS X 10.5)

Did we not warn you about "Upgrade Install?"; APE also to blame

Hundreds of users are reporting an inability to properly startup after installing Mac OS X 10.5 (Leopard). This issue is typified by a successful installation, but a persistent blue screen on the subsequent restart, requiring a forced shut down. Unsurprisingly, virtually every user reporting this problem used a straight upgrade ("Upgrade Install") rather than performing an Archive and Install or Erase and Install as we previously recommended. You could argue that (in theory) most users select "Upgrade Install," hence users reporting problems will cite it. However, the facts that literally every report we've received of this problem so far implicates "Upgrade Install," and many users report that going back and performing an Archive and Install or Erase and Install instead solves the issue are telling.

Also, while (as we've noted for every incremental Tiger update) the first restart can be longer than usual -- up to 10 minutes or more in some cases -- many users have waited patiently for more than 60 minutes: a strong indicator that something has gone horribly wrong.

Some sample reports from a rapidly growing Apple Discussions thread:

  • "I'm upgrading my 20" iMac (Core Duo) at the moment and the installation 'completed', then the computer rebooted and it has been sitting on a plain blue screen for the past 30 minutes. Did a (straight) upgrade."
  • "15" MBP. Selected Upgrade. Ran through the install. Rebooted. Blue screen, black cursor, no activity I waited about 30 minutes before forcing the reboot. After bootup, same screen. I have Apple Care on the MBP so I called in."
  • "I received my copy of Leopard today and it is the same thing here with my PowerBook G4. It keeps getting stuck with the empty blue screen while booting. I tried rebooting a few times but it does not help at all. The vents are blowing full throttle so something is calculating, I guess. The mouse is moving but that is it. I am waiting for an hour now. [...] Maybe I should add that I did a straight update of my 10.4.10 and did not install the custom language support and some printers. Everything else remained standard."

MacFixIt reader K Stern adds:

"Installing on a PB 1.67. 2megs of RAM. Running 10.4.10. Ran Disk Warrior before install. After doing a Upgrade Install it reboots. Gray screen for a few seconds then... Blue screen for 1 sec then... Blue Screen again then nothing. Waited over 1/2 hour. Noticed my fans running hard and lots of heat. What I've done so far: Shut down; Started up from Install disk; Run Disk Utility (no problems found); Tried to do it again with same negative results."

The obvious solution, which has already proven successful for most users experiencing this problem, is to simply boot again from your Leopard DVD by holding down the "C" key at startup and choose one of the Archive and Install or Erase and Install options. See this article for a description of the different install types.

Remove APE haxies (ShapeShifer, etc.)

Another potential cause for this issue that shouldn't be shocking if you've routinely paid attention to MacFixIt: the presence of APE modules. Before installing Leopard, remove APE modules.

Again, some pertinent posts from Apple's Discussion boads:

  • "I managed to fix this issue with my machine. I was getting the BSoD (for shame, Apple, doing the same thing we used to be able to prod Windows users about) and suspected it to be APE. Rather than go through the insanity of uninstall/restore/archive and reinstall, etc, I decided to try to manually uninstall APE and continue booting. It worked"
  • "This solved it for me. I didn't have the (APE) prefpane loaded, but the others were there and removing them fixed it perfectly."

If you've already installed Leopard, can't boot, and need to remove the haxies, restart into single user mode by holding down the Command and S keys simultaneously during startup. Next, enter the following commands, pressing return after each (as compiled by Apple Discussions poster Chris Mcculoh).

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

Reboot normally and check for proper startup.

Interestingly enough, since these haxies are stored at a system level, they would have been eliminated (and, in turn, the startup problem eliminated) by using an "Archive and Install" or "Erase and Install" rather than "Upgrade Install."

Other fixes

There are also a few other fixes that might not necessitate the aforementioned, most culled from our tutorial "Startup fails (particularly after a system or security update); solving". However, we have to stress this point: if something has gone wrong during the installation of Mac OS X 10.5 that's causing the startup issue, these fixes may be only temporary and you might encounter other problems later. The only surefire way eliminate such problems is to perform a re-install and select something other than "Upgrade Install.":

Disconnect external devices Try removing any FireWire, USB or other external peripherals then re-attempting startup.

Take this Apple Discussions poster:

"I had heaps of stuff connected to my laptop, I disconnected this before I restarted and this seemed to help."

Or this one (with a slightly different issue, in that Leopard wouldn't complete its installation):

"I had the 10.5 install hang midway thru the 'Installing' screen on my trust old mac mini. It didn't move for about an hour so I hit the power off and disconnected all additional devices (2 x LaCie HDDS, EyeTV box, Apple TV) and changed from wireless mouse to wired. So far so good - the install has now proceeded way beyond where it was and tells me I have 15 mins left (the estimates that the install for time to complete are way out btw)."

Boot in Safe mode Try starting in Safe mode (hold the "Shift" key while you startup), then delete some cache and .plist files to make sure their corruption isn't at fault. Since many tools for doing this haven't been updated for Leopard, there is a manual process which involves dragging the following files to the trash:

  • (a folder in /System/Library/Caches)
  • Extensions.kextcache (a file in /System/Library)
  • Extensions.mkext (a file in /System/Library/)
  • (a folder in /Library/Caches/)
  • (a file in /Library/Preferences/)
  • Files that start with (in /Library/Caches)

You will be prompted to enter your administrator password when dragging these files to the trash. You may need to restart after moving them to the trash.

Next, go to the Accounts pane of System Preferences and click the "Login Items" tab. Select all the login items and click Remove, then restart. Also, check the /Library/StartupItems and /System/Library/StartupItems folders and remove any third-party items.

Finally, look in the folder /System/Library/Extensions for any third-party kernel extensions (files that end in .kext). Remove the kernel extensions and check for persistence of the issue.


  • previously recommended
  • noted
  • Apple Discussions thread
  • article
  • Chris Mcculoh
  • "Startup fails (particularly after a system or security update); solving"
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