Twitter
RSSTutorial: Change iPhone/iPod Touch System Version
Feb 08
Okay, this may not be the first tutorial on this. I think I’ve seen others, but I’m quite sure they involve a different method/are in obscure places like blog comments.
Not to mention, this is something I originally learned to do in desktop OSX, to get Safari 4 installed in 10.5.5. A tutorial for changing the desktop OSX system version would work unmodified on iPhone OS. It’s the exact same file that requires modification.
Anyway, now to get to the point.
If you have a jailbroken iPhone, you’ll know how much of a pain it is to install iPhone OS updates, considering they ruin your jailbreak, creating a potential hours of work. Meaning minor updates are generally best to avoid. For example, my iPhone 3GS still has iPhone OS 3.1 on it, which it came with when I got it in December. But, I went to download a game called “FallDown!” and was greeted by this message.
Considering I’m not going to upgrade just to install the one app that’s ever presented me with this error, I thought, “If I can bypass software that requires minor updates on OSX, why can’t I on iPhone OS using the same method?”
Let’s get started, shall we? 
Prerequisites:
1. A jailbroken iPhone/iPod Touch (otherwise, just install the update, it’s no trouble at all for you).
2. A file browser. I’ll be using iFile, as I have in all my past tutorials.
Steps:
1. Open iFile (or another file browser of your choice).
2. Browse to /System/Library/CoreServices/SystemVersion.plist and back it up.
3. Open it, and select Edit.
4. Go to the line that says “Product Version” and look under it. Change the version number from whatever it is (in my case 3.1) to whatever you want it to be. I’ve changed it to stuff like 4.0 before to fool people into thinking I have it (this did cause problems, mainly with AppSync, which expected 3.x, so every time I did anything in Cydia, AppSync uninstalled itself). But for now, I’ve changed it to 3.1.2 so I could install FallDown!
5. Select Save to save the file.
It actually doesn’t seem to require a restart or even a respring, so…
6. Install apps that claim to have compatibility problems.
And notice it’s working! 
Compatibility problems… or not.
Please do note: Some apps probably do have actual compatibility problems. Heck, this one may. I only played it for ten seconds, then got the idea to write this tutorial and had to do it before I forgot.
