1 Reply
      Latest reply on Nov 28, 2019 2:16 AM by eskimo
      superleo_whiz Level 1 Level 1 (0 points)

        I have an app which is Live on Appstore and has several daily active users. Recently a user reported consistent crash at random sports on his device. By reviewing Crashlytics, I found out that the crash is being produced on iPhone XS Max with iOS 13.2 and  the stack trace has following information:

        Crashed: com.apple.main-thread
        0  libsystem_platform.dylib       0x1b3bdbf64 os_unfair_lock_lock + 16
        1  CoreFoundation                 0x1b3da9bc4 -[__NSDictionaryM dealloc] + 76
        2  ???                            0x1c1ba981b3c0a400 (Missing)
        3  ???                            0x0 (Missing)
        4  ???                            0x0 (Missing)
        5  ???                            0x2766d381b3c0a400 (Missing)
        6  ???                            0x3d5f6c01b3e1b600 (Missing)
        7  ???                            0xd271c81b3da6180 (Missing)
        8  ???                            0x3542181b3c0a400 (Missing)
        9  ???                            0x0 (Missing)
        10 ???                            0x2d16ca81b3da9c00 (Missing)
        11 ???                            0x0 (Missing)
        12 ???                            0x7e19e401b3afac00 (Missing)
        13 ???                            0x7f368801b3b7d000 (Missing)
        14 ???                            0x5b22a781b3b88c00 (Missing)
        15 ???                            0x0 (Missing)
        16 ???                            0x3d0fc001b3e4bc00 (Missing)
        17 ???                            0x56480c81b3e4b000 (Missing)
        18 ???                            0x0 (Missing)
        19 ???                            0x192a7901b7f6b800 (Missing)
        20 ???                            0x254f2401008b0200 (Missing)
        21 libdyld.dylib                  0x1b3ccaf30 start + 4

        This is not a lot of information, but this is what I am getting through crashlytics. I have several devices including iphone 6, 6s and X, but unable to reproduce similar crash.

        Can anyone suggest what could be the possible issue here?

        • Re: App crashes on iPhone XS max with os_unfair_lock_lock
          eskimo Apple Staff Apple Staff (12,425 points)

          It’s hard to offer any concrete advice based on a third-party crash report.  If you can post an Apple crash report, I can take a more in-depth look.

          However, frame 1 of the backtrace shows that you’re crashing in -[__NSDictionaryM dealloc], which is the the -dealloc method for NSMutableDictionary.  Such a problem is usually the result of memory management bugs, and so I recommend that you use the standard memory debugging tools to try to flush it out.

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