Analyzing Xamarin.iOS Crash Report

Question

Our Xamarin Forms app is crashing intermittently on one of our iOS test devices, and I'm having a very hard time finding anything useful in the crash report.

All of the tutorials and examples I have found seem to reference line numbers and methods/properties from the application itself but all I am seeing here are mono library calls.

I'm also unable to reproduce the issue locally. Can anyone offer any guidance, or suggest a good resource I could use to determine what this crash report is actually reporting:

Exception Type:  EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Exception Note:  EXC_CORPSE_NOTIFY
Triggered by Thread:  0

Thread 0 name:
Thread 0 Crashed:
0   libsystem_kernel.dylib          0x0000000189423014 __pthread_kill + 8
1   libsystem_pthread.dylib         0x00000001894eb450 pthread_kill + 112 (pthread.c:1366)
2   libsystem_c.dylib               0x0000000189397400 abort + 140 (abort.c:91)
3   ESPMobileiOS                    0x00000001000476a8 mono_handle_native_sigsegv (mini-exceptions.c:2420)
4   libsystem_platform.dylib        0x00000001894e5348 _sigtramp + 52 (sigtramp.c:115)
5   libsystem_pthread.dylib         0x00000001894eb450 pthread_kill + 112 (pthread.c:1366)
6   libsystem_c.dylib               0x0000000189397400 abort + 140 (abort.c:91)
7   ESPMobileiOS                    0x000000010012fa04 print_all_exceptions(MonoObject*) (runtime.m:997)
8   ESPMobileiOS                    0x0000000100047de0 mono_invoke_unhandled_exception_hook (mini-exceptions.c:2873)
9   ESPMobileiOS                    0x000000010004733c mono_handle_exception_internal (mini-exceptions.c:1798)
10  ESPMobileiOS                    0x000000010004641c mono_handle_exception (mini-exceptions.c:2027)
11  ESPMobileiOS                    0x000000010003ef18 mono_arm_throw_exception (exceptions-arm64.c:390)
12  ESPMobileiOS                    0x00000001004de4e8 throw_exception + 168
13  ESPMobileiOS                    0x00000001002f67cc System_Runtime_ExceptionServices_ExceptionDispatchInfo_Throw + 44
14  ESPMobileiOS                    0x00000001002f4d20 System_Runtime_CompilerServices_AsyncMethodBuilderCore__ThrowAsyncm__0_object + 80
15  ESPMobileiOS                    0x000000010018cbd8 UIKit_UIKitSynchronizationContext__Postc__AnonStorey0__m__0 (UIKitSynchronizationContext.cs:24)
16  ESPMobileiOS                    0x00000001001aa3a4 Foundation_NSAsyncActionDispatcher_Apply (NSAction.cs:163)
17  ESPMobileiOS                    0x00000001004a9f94 wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr + 244
18  ESPMobileiOS                    0x000000010005433c mono_jit_runtime_invoke (mini-runtime.c:2524)
19  ESPMobileiOS                    0x00000001000b0918 do_runtime_invoke (object.c:2809)
20  ESPMobileiOS                    0x00000001000b0874 mono_runtime_invoke (object.c:2967)
21  ESPMobileiOS                    0x00000001011a98e4 native_to_managed_trampoline_3(objc_object*, objc_selector*, _MonoMethod**, char const*, char const*) (registrar.m:103)
22  ESPMobileiOS                    0x00000001011a9fdc -[__MonoMac_NSAsyncActionDispatcher xamarinApplySelector] (registrar.m:6678)
23  Foundation                      0x000000018af69048 __NSThreadPerformPerform + 340 (NSThread.m:1247)
24  CoreFoundation                  0x000000018a402b5c __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 24 (CFRunLoop.c:1943)
25  CoreFoundation                  0x000000018a4024a4 __CFRunLoopDoSources0 + 524 (CFRunLoop.c:1989)
26  CoreFoundation                  0x000000018a4000a4 __CFRunLoopRun + 804 (CFRunLoop.c:2821)
27  CoreFoundation                  0x000000018a32e2b8 CFRunLoopRunSpecific + 444 (CFRunLoop.c:3113)
28  GraphicsServices                0x000000018bde2198 GSEventRunModal + 180 (GSEvent.c:2245)
29  UIKit                           0x00000001903757fc -[UIApplication _run] + 684 (UIApplication.m:2650)
30  UIKit                           0x0000000190370534 UIApplicationMain + 208 (UIApplication.m:4092)
31  ESPMobileiOS                    0x00000001001f7de4 wrapper_managed_to_native_UIKit_UIApplication_UIApplicationMain_int_string___intptr_intptr (/<unknown>:1)
32  ESPMobileiOS                    0x000000010016a55c UIKit_UIApplication_Main_string___intptr_intptr (UIApplication.cs:79)
33  ESPMobileiOS                    0x000000010016a51c UIKit_UIApplication_Main_string___string_string (UIApplication.cs:63)
34  ESPMobileiOS                    0x0000000100134214 ESPMobile_iOS_Application_Main_string__ (Main.cs:13)
35  ESPMobileiOS                    0x00000001004a9f94 wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr + 244
36  ESPMobileiOS                    0x000000010005433c mono_jit_runtime_invoke (mini-runtime.c:2524)
37  ESPMobileiOS                    0x00000001000b0918 do_runtime_invoke (object.c:2809)
38  ESPMobileiOS                    0x00000001000b293c mono_runtime_exec_main (object.c:4585)
39  ESPMobileiOS                    0x00000001000b2558 mono_runtime_run_main (object.c:4134)
40  ESPMobileiOS                    0x000000010003e738 mono_jit_exec (driver.g.c:1048)
41  ESPMobileiOS                    0x0000000100133b68 xamarin_main (monotouch-main.m:487)
42  ESPMobileiOS                    0x00000001011cef80 main (main.arm64.m:115)
43  libdyld.dylib                   0x00000001893115b8 start + 4

Answer 1

What I can see, is that something is going wrong when you try to run some code on the ui thread. The following line tells me this UIKit_UIKitSynchronizationContext__Postc__AnonStorey0__m__0 (UIKitSynchronizationContext.cs:24).

It's very hard to tell exactly what the problem is or in which file the problem is. Maybe implement insights are another crash logger. So you get more info about the crash.