IOS – My fiance’s iPhone 4 is still running on iOS 5, now that 6.1.3 has been released can I upgrade her to 6.1.2 so she can use evasion

iPhone 4 GSM Black:

I had the same issue when I updated to 6.1.2 from my previous version 5.1.1 when the evasi0n jailbreak came out. I solved the problem by restoring to the factory default. Then I went through the beginning steps of the iphone introduction, when i open and logged in to gamecenter everything came through pretty smooth... I jailbreaked it after I restored and gamecenter still worked smoothly. Then I restored to my last back-up and opened gamecenter after it all loaded up and everything is still working fine. Hopefully this simple troubleshooting helped out. It did for me.

The final iOS rev for iPhone 3G is 4.2.1, and you could always save a backup before upgrading and restor to the 3.X version if 4.2.1 was too much of a hog.

Hope this helps!

Edit: This thread says its not even worth it. 4.2.1 is crippling to the device.