Fix for the never-ending Apple logo during iPhone boot problem

So, the last few days, I’ve had a quite weird issue with my iPhone. It locks up, and after a force reset, it never does anything else than showing the Apple logo. However, it does connect to Wifi for about 5 minutes so i can SSH into the phone.

So far, I’ve been resetting the phone from scratch, but with help from eric in #iphone on irc.saurik.com I managed to figure out a solution.

For now I’m just gonna write up the steps required to fix it. I’ll update the post later with details of why and how this happens.

The Fix

First of all, your phone still has to connect to your wifi network so you get SSH access, even tho it’s still only displaying the Apple logo. It will probably disable wifi after about 5 minutes, so you gotta move faster than a snail at least.

Don’t try this if you don’t know what you’re doing. Also, this is for the 2.0/2.1 iPhone software, but might also work on 1.x.

1. SSH into the phone as root, cd to /System/Library/SystemConfiguration/ and rename mobilewatchdog.bundle to mobilewatchdog.bundle_x.

2. cd to /private/var/mobile/Library/Caches/ and remove any files which names begin with com.apple.mobile.installation.

3. Reboot the phone, and like magic it should start up like normal, in 2-15 minutes depending on how many apps you have installed.

4. SSH in again and rename the mobilewatchdog.bundle_x folder back to mobilewatchdog.bundle in /System/Library/SystemConfiguration/, and reboot.

The Cause

The problem’s root is a combination of how App Store apps are stored on the phone, and a safety process called mobilewatchdog which ensures that the Springboard doesn’t lock up.

Myself, I’ve mainly had it triggered by installing an app with Cydia which has a Springboard icon. As you surely have noticed, Cydia on iPhone software 2.0.x doesn’t need to restart the Springboard anymore for new applications to show. It seems to use a similar method as the App Store to dynamically create new application icons.

The problem is that sometimes when Cydia adds an application icon, the Springboard flips out and loses its cached list of installed applications. That list is required cause the App Store apps are stored in their own little sandbox protected folders, which means that it’s a bit more complicated than just getting a directory listing to see which applications are installed. And it takes some time to scan for all installed applications.

And that’s where the problem starts. There’s a background daemon called mobilewatchdog, who’s sole purpose is to make sure that the Springboard does not crash or lock up. In the event of the Springboard locking up or crashing, mobilewatchdog will force quit and relaunch it. Sounds good right? Right, as long as the Springboard doesn’t have to rescan for installed applications.

As it seems, when the Springboard scans for applications, it’s too busy to respond to mobilewatchdog’s checks. And mobilewatchdog being very impatient, only waits 2 seconds for an answer from Springboard. So if it doesn’t get a response within 2 seconds, it force quits the Springboard and relaunches it. At this point, Springboard just starts rescanning for installed applications again and gets to busy to respond to mobilewatchdog again, and the circule continues for all eternity.

So the solution was pretty obvious. Disable mobilewatchdog temporarily so Springboard get’s time to find all installed applications. I originally tried some plist configurations as was suggested by syslog dumps from the mobilewatchdog daemon itself, they didn’t work tho. So being desperate, and crazy, I simply renamed the mobilewatchdog bundle rendering it unusable, hoping that its launched simply based on file name, and nothing else fails due to it referencing it. Luckily enough, it works.

Springboard was given enough time to find all my installed applications and launch like normal. It had however missed a few apps, so I went looking for the cached list of installed apps, which was where I expected it to be. In /private/var/mobile/Library/Caches/. Removing the cache files forces Springboard to scan for apps again, and with mobilewatchdog out of the picture, it works perfectly.

I’ve only tested this on 2.0.2, but should be exactly the same for all 2.0.x software. I’ve tested this on both 2.0.2 and 2.1 with success. I have had the same issue on 1.1.4 tho when using Installer. However, I don’t know if its the same issue or not. If this happens to work for the same issue on 1.x, please let me know :)

It was thanks to eric in #iphone on irc.saurik.com that i figured out this solution. He had previously had this issue, and worked with saurik to figure out what was going on. Without being pointed in the right direction, I wouldn’t have had a clue of where to start, and just ended up swearing my head off and resetting my iPhone yet again.