Xcode 4.2 debug doesn’t symbolicate stack call

Nothing I tried would fix this (tried both compilers, both debuggers, etc.)
After upgrading XCode for the iOS 5 update, no stack traces seemed to work.

However, I have found an effective work-around – creating my own exception handler (which is also useful for other reasons). First, create a function that will handle the error and output it to the console (as well as whatever else you want to do with it):

void uncaughtExceptionHandler(NSException *exception) {
    NSLog(@"CRASH: %@", exception);
    NSLog(@"Stack Trace: %@", [exception callStackSymbols]);
    // Internal error reporting
}

Next, add the exception handler to your app delegate:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{   
    NSSetUncaughtExceptionHandler(&uncaughtExceptionHandler);
    // Normal launch stuff
}

That’s it!

If this doesn’t work, then there are only two possible reasons:

1. Something is overwriting your NSSetUncaughtExceptionHandler call (there can be only one handler for your entire app). For example, some 3rd party libraries set their own uncaughtExceptionHandler. So, try setting it at the END of your didFinishLaunchingWithOptions function (or selectively disabling 3rd party libraries). Or better yet, set a symbolic break point on NSSetUncaughtExceptionHandler to quickly see who is calling it. What you may want to do is to modify your current one rather than adding another one.
2. You’re not actually encountering an exception (for example, EXC_BAD_ACCESS is not an exception; credit to @Erik B’s comments, below)