UPDATED -- 10.5.6 Breaks DFU Mode?
Three official options from dev team
1. Replace the following plugin kexts from within IOUSBFamily.kext with the ones from 10.5.5 and then rebuild kextcache.
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.
Cash Update: So I've been playing with this for a few hours now. 10.5.6 will not let you use DFU mode to restore custom firmware to a phone that IS NOT already pwnd. Replacing MobileDevice.framework with the previous version does not seem to matter either -- have not tried replacing the framework and downgrading iTunes or replacing other frameworks/haven't ahd time to dig in to the drivers and replace yet. A USB hub will work just fine with no issues at all to pwn on 10.5.6 with the latest iTunes. Had zero issues with my powered USB hub. Tired now and not interested in restoring anymore tonight so some updates from our members. One report says that QuickPwn works fine. If your iPhone is ALREADY pwnd and you need to restore with a custom firmware it has been reported to work. Windows users report no issues at all (of course) this is just a mac thing with the 10.5.6 update.
According to some iPhone news sites, the latest Mac OS X release (10.5.6) disables the use of DFU mode. This can be bypassed by plugging your iPhone into a USB hub. The Dev Team has been notified on this and a fix will probably be here soon. For now, do not update to 10.5.6 if you want to jailbreak your device unless you absolutely have to...or have a spare USB hub.
Basically it scattered reports are claiming that everything will work properly if you are connected to a USB hub instead of directly to the computer. The idea behind this is that the drivers for the USB hub will still allow you to connect in DFU and do your thing where the updated drivers in 10.5.6 when you connect directly to the computer would be fubared. What also would probably work is if you took the 10.5.5 [script]drivers[/script] framework and stuck it on 10.5.6.
Here at MMi we will confirm things sometime tonight. If you have tested this out yourself post up!
Oh and thanks to strchris for making his first post on our forums
earlier today to warn the rest of us jailbreakers of the potential problem.