Downgraded back to OS 3.1.3 and cannot restore backup! says software too old - pls help

[draxz1289]

i Just downgraded to 3.1.3 from iOS 4 when I try to restore it says that the iphone software is too old.

I have tried to restore it using official firmware 3.1.3 and jailbroken 3.1.3
please help

I am on a Mac

[Will01]

This is a standard error. I dont know if there is a workaround. Personally I would have backed up with something other than iTunes and restored that when you downgraded.