malloc: *** error: incorrect checksum for freed object - object was probably modified after being freed

Question

I have a big problem with my iOS App: it crashes sometimes without detailed debug error. The stack trace is empty. These are the only two lines in the stack trace:

Answer 1

Since you're in the debugger, you should look at the memory location 0x208a7614 and see what's there. The data in memory may be helpful in figuring out what's going wrong.

What's happening is one of the following:

1. you are freeing an object twice,

2. you are freeing a pointer that was never allocated

3. you are writing through an invalid pointer which previously pointed to an object which was already freed

Since the stack trace is coming up empty, it might be useful to add some debugging log statements to your code at various places to see if you can narrow down where in the code the problem lies. Using the memory tools in Instruments might also help. You could try turning on NSZombies, but this looks like a C allocation problem and not an Objective-C one.

Also, is anything else written to the console before the crash? If so, it may point you to where the problem is coming from.