Once I tried to change the default startup disk on my Mac running Snow Leopard and the following error appeared: “you can’t change the startup disk to the selected disk. Building boot caches on boot helper partition failed”.
At first I was trying to figure what’s a boot helper partition and where do I find it, but eventually I decided to take a look at com.apple.Boot.plist file, which appeared to be non-existent in it’s regular place.
So I created one by myself. In Terminal:
sudo nano /Library/Preferences/SystemConfiguration/com.apple.Boot.plist
There inserted the default code:
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http:// www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>Kernel</key> <string>mach_kernel</string> <key>Kernel Flags</key> <string></string> </dict> </plist>
(Cmd+X to save the file).
This solved the problem for me.