iOS app crashing in apple app review but completely unreproducible locally

Question

we have recently developed a Xamarin forms app which is built for both Android and iOS. The Android version is on the google play store and is working as expected. The iOS version works on all of our devices and emulators but is crashing when apple test it during their app review process using iOS 9.3.3. We have symbolicated the crash report but are at a loss as to what is possibly causing the crash.

The symbolicated crash report is below and would greatly appreciate any assistance people can provide that will help us track down the cause of the crash.

Incident Identifier: 1D827CDB-F42D-457B-AE32-F887824E7EFE CrashReporter Key: ed6d5c5e7f0dc0721d5e88ce52e57230f0fb842f Hardware Model: xxx Process: SwiftPOSMemberPortaliOS [1615] Path:
/private/var/containers/Bundle/Application/DB6ED5ED-7A9A-4809-A92F-514EC1BC35C9/SwiftPOSMemberPortaliOS.app/SwiftPOSMemberPortaliOS Identifier: com.swiftpos.loyalty Version: 4 (6.48.4) Code Type: ARM-64 (Native) Parent Process:
launchd [1]

Date/Time: 2016-07-25 17:31:45.45 -0700 Launch Time:
2016-07-25 17:31:43.43 -0700 OS Version: iOS 9.3.3 (13G34) Report Version: 105

Exception Type: EXC_BAD_ACCESS (SIGABRT) Exception Subtype: KERN_INVALID_ADDRESS at 0x0000000000000000 Triggered by Thread: 0

Filtered syslog: None found

Last Exception Backtrace: 0 CoreFoundation
0x182ce2db0 0x182bb8000 + 1224112 1 libobjc.A.dylib
0x182347f80 0x182340000 + 32640 2 CoreFoundation
0x182ce2a70 0x182bb8000 + 1223280 3 SwiftPOSMemberPortaliOS
0x100f6f078 WriteZStream + 13814828 4 SwiftPOSMemberPortaliOS
0x100f5f62c WriteZStream + 13750752 5 SwiftPOSMemberPortaliOS
0x100f5f46c WriteZStream + 13750304 6 SwiftPOSMemberPortaliOS
0x100f612e8 WriteZStream + 13758108 7 SwiftPOSMemberPortaliOS
0x1004f9e84 WriteZStream + 2849336 8 SwiftPOSMemberPortaliOS
0x10016bfbc plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 252664 9 SwiftPOSMemberPortaliOS 0x1001c2ae4 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 607776 10 SwiftPOSMemberPortaliOS 0x1001c766c plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 627112 11 SwiftPOSMemberPortaliOS 0x1001c7264 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 626080 12 SwiftPOSMemberPortaliOS 0x10015f214 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 200016 13 SwiftPOSMemberPortaliOS 0x10015e8fc plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 197688 14 SwiftPOSMemberPortaliOS 0x100157a54 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 169360 15 SwiftPOSMemberPortaliOS 0x10052f388 WriteZStream + 3067708 16 SwiftPOSMemberPortaliOS 0x100358aac WriteZStream + 1140320 17 SwiftPOSMemberPortaliOS 0x1003574b0 WriteZStream + 1134692 18 SwiftPOSMemberPortaliOS 0x10094e3e8 WriteZStream + 7389084 19 SwiftPOSMemberPortaliOS 0x10098b944 WriteZStream + 7640312 20 SwiftPOSMemberPortaliOS 0x1004f9e84 WriteZStream + 2849336 21 SwiftPOSMemberPortaliOS 0x10016bfbc plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 252664 22 SwiftPOSMemberPortaliOS 0x1001c2ae4 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 607776 23 SwiftPOSMemberPortaliOS 0x100f744cc WriteZStream + 13836416 24 SwiftPOSMemberPortaliOS 0x100f74fc8 WriteZStream + 13839228 25 Foundation 0x1836b802c 0x1835c4000 + 999468 26 CoreFoundation 0x182c9909c 0x182bb8000 + 921756 27 CoreFoundation 0x182c98b30 0x182bb8000 + 920368 28 CoreFoundation 0x182c96830 0x182bb8000 + 911408 29 CoreFoundation 0x182bc0c50 0x182bb8000 + 35920 30 GraphicsServices 0x1844a8088 0x18449c000 + 49288 31 UIKit 0x187ea2088 0x187e24000 + 516232 32 SwiftPOSMemberPortaliOS 0x1009d0b64 WriteZStream + 7923480 33 SwiftPOSMemberPortaliOS 0x10093cb3c WriteZStream + 7317232 34 SwiftPOSMemberPortaliOS 0x10093cafc WriteZStream + 7317168 35 SwiftPOSMemberPortaliOS 0x1002436c4 WriteZStream + 4728 36 SwiftPOSMemberPortaliOS 0x1004f9e84 WriteZStream + 2849336 37 SwiftPOSMemberPortaliOS 0x10016bfbc plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 252664 38 SwiftPOSMemberPortaliOS 0x1001c2ae4 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 607776 39 SwiftPOSMemberPortaliOS 0x1001c6f34 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 625264 40 SwiftPOSMemberPortaliOS 0x100241ed0 xamarin_GetFolderPath + 1960 41 SwiftPOSMemberPortaliOS
0x100f90f38 WriteZStream + 13953772 42 libdyld.dylib
0x18275e8b8 0x18275c000 + 10424

Global Trace Buffer (reverse chronological seconds): 6148914687.764939 CFNetwork 0x00000001832c58e0 TCP Conn 0x12e7b2840 SSL Handshake DONE 6148914687.955328 CFNetwork 0x00000001832c57f0 TCP Conn 0x12e7b2840 starting SSL negotiation 6148914687.955688 CFNetwork 0x0000000183367e7c TCP Conn 0x12e7b2840 complete. fd: 5, err: 0 6148914687.956469 CFNetwork 0x00000001833693a8 TCP Conn 0x12e7b2840 event 1. err: 0 6148914688.040974 CFNetwork 0x0000000183369480 TCP Conn 0x12e7b2840 started 6148914688.043079 CFNetwork 0x00000001833c3e5c Creating default cookie storage with default identifier 6148914688.043079 CFNetwork 0x00000001833c3e28 Faulting in CFHTTPCookieStorage singleton 6148914688.043085 CFNetwork 0x0000000183415e50 Faulting in NSHTTPCookieStorage singleton

Thread 0 name: tid_c07 Dispatch queue: com.apple.main-thread Thread 0 Crashed: 0 libsystem_kernel.dylib 0x000000018287c11c 0x182860000 + 114972 1 libsystem_pthread.dylib
0x0000000182948ef8 0x182944000 + 20216 2 libsystem_c.dylib
0x00000001827eddc8 0x18278c000 + 400840 3 SwiftPOSMemberPortaliOS
0x000000010011c320 0x1000b4000 + 426784 4 CoreFoundation
0x0000000182ce3138 0x182bb8000 + 1225016 5 libobjc.A.dylib
0x000000018234823c 0x182340000 + 33340 6 SwiftPOSMemberPortaliOS
0x000000010010a290 0x1000b4000 + 352912 7 libc++abi.dylib
0x000000018233af44 0x182320000 + 110404 8 libc++abi.dylib
0x000000018233a85c 0x182320000 + 108636 9 libobjc.A.dylib
0x0000000182348094 0x182340000 + 32916 10 CoreFoundation
0x0000000182ce2a70 0x182bb8000 + 1223280 11 SwiftPOSMemberPortaliOS 0x0000000100f6f078 WriteZStream + 13814828 12 SwiftPOSMemberPortaliOS 0x0000000100f5f62c WriteZStream + 13750752 13 SwiftPOSMemberPortaliOS 0x0000000100f5f46c WriteZStream + 13750304 14 SwiftPOSMemberPortaliOS
0x0000000100f612e8 WriteZStream + 13758108 15 SwiftPOSMemberPortaliOS 0x00000001004f9e84 WriteZStream + 2849336 16 SwiftPOSMemberPortaliOS 0x000000010016bfbc plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 252664 17 SwiftPOSMemberPortaliOS 0x00000001001c2ae4 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 607776 18 SwiftPOSMemberPortaliOS 0x00000001001c766c plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 627112 19 SwiftPOSMemberPortaliOS 0x00000001001c7264 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 626080 20 SwiftPOSMemberPortaliOS 0x000000010015f214 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 200016 21 SwiftPOSMemberPortaliOS 0x000000010015e8fc plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 197688 22 SwiftPOSMemberPortaliOS 0x0000000100157a54 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 169360 23 SwiftPOSMemberPortaliOS 0x000000010052f388 WriteZStream + 3067708 24 SwiftPOSMemberPortaliOS
0x0000000100358aac WriteZStream + 1140320 25 SwiftPOSMemberPortaliOS 0x00000001003574b0 WriteZStream + 1134692 26 SwiftPOSMemberPortaliOS 0x000000010094e3e8 WriteZStream + 7389084 27 SwiftPOSMemberPortaliOS 0x000000010098b944 WriteZStream + 7640312 28 SwiftPOSMemberPortaliOS 0x00000001004f9e84 WriteZStream + 2849336 29 SwiftPOSMemberPortaliOS 0x000000010016bfbc plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 252664 30 SwiftPOSMemberPortaliOS 0x00000001001c2ae4 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 607776 31 SwiftPOSMemberPortaliOS 0x0000000100f744cc WriteZStream + 13836416 32 SwiftPOSMemberPortaliOS
0x0000000100f74fc8 WriteZStream + 13839228 33 Foundation
0x00000001836b802c 0x1835c4000 + 999468 34 CoreFoundation
0x0000000182c9909c 0x182bb8000 + 921756 35 CoreFoundation
0x0000000182c98b30 0x182bb8000 + 920368 36 CoreFoundation
0x0000000182c96830 0x182bb8000 + 911408 37 CoreFoundation
0x0000000182bc0c50 0x182bb8000 + 35920 38 GraphicsServices
0x00000001844a8088 0x18449c000 + 49288 39 UIKit
0x0000000187ea2088 0x187e24000 + 516232 40 SwiftPOSMemberPortaliOS
0x00000001009d0b64 WriteZStream + 7923480 41 SwiftPOSMemberPortaliOS 0x000000010093cb3c WriteZStream + 7317232 42 SwiftPOSMemberPortaliOS 0x000000010093cafc WriteZStream + 7317168 43 SwiftPOSMemberPortaliOS 0x00000001002436c4 WriteZStream + 4728 44 SwiftPOSMemberPortaliOS
0x00000001004f9e84 WriteZStream + 2849336 45 SwiftPOSMemberPortaliOS 0x000000010016bfbc plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 252664 46 SwiftPOSMemberPortaliOS 0x00000001001c2ae4 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 607776 47 SwiftPOSMemberPortaliOS 0x00000001001c6f34 plcrash::BIT::async::dwarf_cfa_state_iterator::next(unsigned int*, plcrash::BIT::async::plcrash_dwarf_cfa_reg_rule_t*, unsigned long long*) + 625264 48 SwiftPOSMemberPortaliOS 0x0000000100241ed0 xamarin_GetFolderPath + 1960 49 SwiftPOSMemberPortaliOS
0x0000000100f90f38 WriteZStream + 13953772 50 libdyld.dylib
0x000000018275e8b8 0x18275c000 + 10424

Answer 1

Thankyou to all who answered. We have found the problem.

Our api session key was the issue. We where not converting the session key expiration time into universal time, so that after deserializing the empty json response, it created a new instance of the type of data and the value was null.

Answer 2

I'm not an expert at iOS stack traces, but these are the parts of it which I consider might be useful clues:

• xamarin_GetFolderPath
• Faulting in NSHTTPCookieStorage singleton

It might be worth asking Apple what sequence of actions they performed before the error occurred. It could be that they are testing a code path which you haven't tested. Also, iOS 9.3.3 has only been out for a few days, are you sure that you have tested on this version?