So I waited a few days to gather some information from users on what has gone wrong with this one before posting if it is safe or if caution is advised. The verdict – caution is advised.

This is the first update that I myself have encountered a problem with so I will attempt to cover what I know as well as what others have found, and how to fix what we’ve seen break.

First problem report I heard was – a kernel panic when running the combo update.

This was related to ApplePolicyControl.kext – when the update loaded it, the system panicked and left things in a non functional state. The users resolution was to re run the combo update from a separate OS X installation, remove the problematic kext when it was done and to then run myFix. This extension is removed by the myHack “Remove Problematic Extensions” feature but that won’t help if it is loaded on a running system by a combo update.

This can be avoided however – if you have an smbios.plist that identifies your system as something that ApplePolicyControl.kext will not panic on – no panic will happen, this was the case with my own system. So you have two options:

1. Create an smbios.plist for your system that ApplePolicyControl.kext will not panic on
2. Run combo update from another OS X installation, targeting the 10.7.x OS X installation you want to update, when finished, run “Remove Problematic Extensions” function from myHack.

Ok, next problem – This happened on my system. When the update was completed, I rebooted. The system panicked on IOPCIFamily.kext. So I rebooted again with -f -v, no panic this time, but the system hung when trying to load AppleHDA, and claimed that kextd was not running. So first I attempted to boot into my ‘fail-safe partition’ which is basically an extra myHack OS X Install Disk for 10.7 that I have on my internal boot partition so I don’t have to dig out my USB stick every time something goes wrong. It hung at the same point….

While I am not entirely sure why the separate partition with a 10.7.0 OS X installer on it was effected by the update the reason for it happening isn’t really important – the solution is simple – I plugged in my USB myHack OS X Install Disk, ran myFix – a full one, not a quick one – and rebooted – everything works fine now. So to sum it up:

1. Ensure your myHack OS X Install Disk is not attached or mounted on the system
2. Run the 10.7.4 update and reboot when it is finished
3. Boot to your myHack OS X Install Disk
4. Run myFix, select full not quick, run, and reboot when it is finished
5. Boot your OS X 10.7.4 installation

The last problem I have seen was reported by a user on the forum. His Nvidia GTX295 stopped working after the update. This is a problem I have seen in past updates and why in the myHack guide I always advise users to backup at minimum their /S/L/E directory prior to running any OS X updates. You may read the thread he opened on the forum HERE

The solution for this problem is as follows, and the following method can be adapted to virtually any hardware device that no longer functions after an OS X update due to Apple’s modifications of the System Extensions:

1. Prior to running an OS X update, always backup /System/Library/Extensions
2. In his case his NVidia graphics no longer work due to updates of the Nvidia graphics so he could either determine exactly which kext is the problem and replace only that one with the one from his 10.7.3 backup, or he could replace all of the nvidia graphics extensions including the frame-buffers
3. Determine which extensions you want to override in /System/Library/Extensions in his case he took all of the Nvidia extensions and frame-buffers
4. Place the extensions from 10.7.3 backup in /Extra/Extensions
5. Run myFix, reboot
6. Boot to OS X 10.7.4

A full list of the NVidia extensions and frame-buffers is in the thread I linked to, the clean way to do it would be to just grab the ones for your card specifically – I will be explaining to him how to figure out which ones he needs in the forum thread.

So there you have it, that is how to avoid the 3 most common problems I have seen thus far with this update. If you encounter a new one please let me know via the forum – I will update this post if needed.

Additionally, keep in mind 10.7.4 is pulling code in from 10.8 so there might be a number of issues for users who are still relying on older graphics or i386 libraries…