iPhone app crashes on 3.1.2 after approvement, but not on 3.2 & 4.0.x

Question

Hi! After App Store approvement my app started to crash on launch on 3.1.2 devices. Debug version installed from Xcode works fine on 3.1.2. Both debug and distribution version from App Store work fine on 3.2 and 4.0.1 devices. From crash log:

Exception Type:  EXC_CRASH (SIGABRT)
Exception Codes: 0x00000000, 0x00000000
Crashed Thread:  0

Any ideas what could be wrong?

Answer 1

Does it crash on start or after a specific scenario?

First you have to make sure that that the target 3.1.2 is unmodded/jailbroken, as it might affect some binaries. Also, make sure that it is the same device that tested both debug and release versions.

Check for any 3.2 (and above) specific messages that you send.

After that, either modify your code and check using respondsTo: as in:

if ([receiver respondsTo:someMessage]) {
    [receiver someMessage];
} else {
    // Some alternative code
}

or modify your version requirement. But be careful about this decision because this will limit your market.