[Unsolved Bug] AppDomain Strangely Unloaded.

AppDomain unloaded randomly. Causing static variables lost, runtime object crash and scene became Invalid.

[2018-04-06 16:44:42 525] appdomain unloaded
0 Unity 0x000000010195b05c _Z13GetStacktracei + 92
1 Unity 0x0000000100bd7c00 _Z17DebugStringToFileRK21DebugStringToFileData + 352
2 Unity 0x0000000100bd59e1 _Z17DebugStringToFilePKciS0_i15LogMessageFlagsiiPFvRK11CppLogEntryE + 97
3 Unity 0x0000000101b15659 _Z35DebugLogHandler_CUSTOM_Internal_Log7LogTypeP10MonoStringP10MonoObject + 505
4 [Mono JITed code] (wrapper managed-to-native) UnityEngine.DebugLogHandler:Internal_Log (UnityEngine.LogType,string,UnityEngine.Object) {0x15f27e638} + 0xcb (0x14f866000 0x14f8661d0) [0x2c8ce4c80 - Unity Child Domain]
5 libmonobdwgc-2.0.dylib 0x000000014b42fa1c mono_jit_runtime_invoke + 2458
6 libmonobdwgc-2.0.dylib 0x000000014b5f28f5 do_runtime_invoke + 88
7 libmonobdwgc-2.0.dylib 0x000000014b5e6026 mono_domain_try_unload + 200
8 libmonobdwgc-2.0.dylib 0x000000014b5e6645 mono_domain_unload + 25
9 Unity 0x0000000100fd25f0 _ZL12UnloadDomainv + 384
10 Unity 0x0000000100fd151e _ZN11MonoManager23CreateAndSetChildDomainEv + 78
11 Unity 0x0000000100fd03e7 _ZN11MonoManager19BeginReloadAssemblyER19DomainReloadingData + 1783
12 Unity 0x0000000100fcfacd _ZN11MonoManager14ReloadAssemblyEb + 125
13 Unity 0x00000001012fc48d _Z23ReloadAllUsedAssembliesb + 621
14 Unity 0x000000010199f519 _ZN11Application9TickTimerEv + 2153
15 Foundation 0x00007fff37b9f739 __NSFireTimer + 83
16 CoreFoundation 0x00007fff35a42064 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20
17 CoreFoundation 0x00007fff35a41cd7 __CFRunLoopDoTimer + 1095
18 CoreFoundation 0x00007fff35a417da __CFRunLoopDoTimers + 346
19 CoreFoundation 0x00007fff35a38dab __CFRunLoopRun + 2427
20 CoreFoundation