How to diagnose a crashing app?

Hello all,

I'm new to Xamarin, and inherited some code from another team, that I can compile and run just fine. I can upload to TestFlight, and install from there to devices, and the app runs smoothly.

The issue I have is as following: when I try to change app version, and install this new app from TestFlight, it crashes on all devices instantly at load. Just changing version number in "iOS Application" build settings is causing this crash.

So, the first question is: how to properly update app version? Am I doing it right? I'm not sure.

Next, how to diagnose this issue and find the root cause? In device console I see errors like

<Critical>: * Assertion at ../../../../../mono/mono/metadata/class.c:5594,
condition `!mono_loader_get_last_error ()' not met

In device logs there are crash reports pointing to some third-party library failing to initialize:

4   XxHelper                    0x0073bfd2 monoeg_assertion_message (goutput.c:197)
5   XxHelper                    0x0077e1d8 mono_class_create_from_typedef (class.c:5594)
6   XxHelper                    0x0077eaca mono_class_get_full (class.c:7092)
7   XxHelper                    0x0077eba2 mono_class_get (class.c:7188)
8   XxHelper                    0x00737940 mono_get_method_from_token (loader.c:1745)
9   XxHelper                    0x007375fa mono_get_method_full (loader.c:1835)
10  XxHelper                    0x0073730e mono_get_method (loader.c:1807)
11  XxHelper                    0x00716164 mono_aot_find_jit_info (aot-runtime.c:2791)
12  XxHelper                    0x0079b094 mono_jit_info_table_find (domain.c:407)
13  XxHelper                    0x00757288 mini_jit_info_table_find (mini-exceptions.c:1135)
14  XxHelper                    0x0074669e mono_arch_find_jit_info (exceptions-arm.c:461)
15  XxHelper                    0x0075782c mono_find_jit_info_ext (mini-exceptions.c:376)
16  XxHelper                    0x00758246 mono_walk_stack_full (mini-exceptions.c:825)
17  XxHelper                    0x007583f4 mono_walk_stack_with_state (mini-exceptions.c:771)
18  XxHelper                    0x0075845c mono_walk_stack (mini-exceptions.c:785)
19  XxHelper                    0x00758514 mono_handle_native_sigsegv (mini-exceptions.c:2302)
20  XxHelper                    0x00766824 mono_sigsegv_signal_handler (mini.c:6565)
21  libsystem_c.dylib               0x39d93e90 _sigtramp + 40
22  XxHelper                    0x007672b2 mono_resolve_patch_target (mini.c:3358)
23  XxHelper                    0x007672b2 mono_resolve_patch_target (mini.c:3358)
24  XxHelper                    0x00717f34 load_method (aot-runtime.c:3241)
25  XxHelper                    0x007189ce mono_aot_get_method (aot-runtime.c:3637)
26  XxHelper                    0x00767866 mono_jit_compile_method_with_opt (mini.c:5658)
27  XxHelper                    0x0076596c mono_jit_compile_method (mini.c:6078)
28  XxHelper                    0x00769452 mono_compile_method (object.c:587)
29  XxHelper                    0x00760e8e mono_delegate_trampoline (mini-trampolines.c:1057)
30  XxHelper                    0x002c8b40 generic_trampoline_delegate + 120
31  XxHelper                    0x006b9eb4 Cirrious_MvvmCross_Binding_MvxBaseBindingBuilder_RegisterTargetFactory (MvxBaseBindingBuilder.cs:59)
32  XxHelper                    0x006b9d34 Cirrious_MvvmCross_Binding_MvxBaseBindingBuilder_DoRegistration (MvxBaseBindingBuilder.cs:34)
33  XxHelper                    0x006a53f8 Cirrious_MvvmCross_Binding_Touch_MvxBaseTouchBindingSetup_InitialiseBindingBuilder (/<unknown>:1)
34  XxHelper                    0x006a53b4 Cirrious_MvvmCross_Binding_Touch_MvxBaseTouchBindingSetup_InitializeLastChance (/<unknown>:1)

How should I proceed with this?