Apple released the Mac OS X 10.5.6 update to Leopard, which has reportedly has caused issues with the iPhone DFU mode. Here’s more from the iPhone Dev Team. It was originally believed that the update and issues reported with the iPhone DFU mode was intentional, however this doesn’t look to be the case.

DFU Issues in OS X 10.5.6

Lots of users have been experiencing problems with the use of DFU mode after applying yesterday’s 10.5.6 system update.

We believe this behavior is due to a kernel bug not a specific countermeasure by Apple. Possible fixes are (try at your own risk!) -

1. Replace the following plugin kexts from within IOUSBFamily.kext with the ones from 10.5.5 and then rebuild kextcache (if you don’t understand this, then you shouldn’t attempt it!)

/System/Library/Extensions/IOUSBFamily.kext/Contents/PlugIns/AppleUSBHub.kext

/System/Library/Extensions/IOUSBFamily.kext/Contents/PlugIns/IOUSBCompositeDriver.kext

2. Use a USB hub in-between the DFU device and the Mac and insert/reinsert the iPhone’s USB cable.

3. Use a PwnageTool created .ipsw on Windows! Oh the irony!

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