Very rare crash- this is the first and only time I have seen it. Hopefully the callstack will give some info as a reliable repro will be difficult to find.

All I did was click a button that shows a dialog in my app by activating a hierarchy under the ui canvas I have set up.

0x00007FFDE661FD40 (mono-2.0-bdwgc) [c:\buildslave\mono\build\mono\mini\mini-trampolines.c:587] common_call_trampoline
0x00007FFDE66227A2 (mono-2.0-bdwgc) [c:\buildslave\mono\build\mono\mini\mini-trampolines.c:911] mono_vcall_trampoline
ERROR: SymGetSymFromAddr64, GetLastError: 'The specified module could not be found.' (Address: 000000000FBE1838)
ERROR: SymGetModuleInfo64, GetLastError: 'A dynamic link library (DLL) initialization routine failed.' (Address: 000000000FBE1838)
0x000000000FBE1838 ((<unknown>)) (function-name not available)
0x0000000038D6B29C (Mono JIT Code) System.Collections.Generic.Stack`1<T_REF>:Push (T_REF)
0x0000000038D6AF10 (Mono JIT Code) [C:\buildslave\unity\build\Extensions\guisystem\UnityEngine.UI\UI\Core\Utility\ObjectPool.cs:46] UnityEngine.UI.ObjectPool`1<T_REF>:Release (T_REF)
0x000000003A485712 (Mono JIT Code) [C:\buildslave\unity\build\Extensions\guisystem\UnityEngine.UI\UI\Core\Utility\ListPool.cs:20] UnityEngine.UI.ListPool`1<UnityEngine.Vector3>:Release (System.Collections.Generic.List`1<UnityEngine.Vector3>)
0x000000003A4852D5 (Mono JIT Code) [C:\buildslave\unity\build\Extensions\guisystem\UnityEngine.UI\UI\Core\Utility\VertexHelper.cs:105] UnityEngine.UI.VertexHelper:Dispose ()
0x000000003A4850CC (Mono JIT Code) [C:\buildslave\unity\build\Extensions\guisystem\UnityEngine.UI\UI\Core\InputField.cs:1942] UnityEngine.UI.InputField:OnFillVBO (UnityEngine.Mesh)
0x000000003A480A24 (Mono JIT Code) [C:\buildslave\unity\build\Extensions\guisystem\UnityEngine.UI\UI\Core\InputField.cs:1914] UnityEngine.UI.InputField:UpdateGeometry ()
0x000000003A4774D4 (Mono JIT Code) [C:\buildslave\unity\build\Extensions\guisystem\UnityEngine.UI\UI\Core\InputField.cs:1872] UnityEngine.UI.InputField:Rebuild (UnityEngine.UI.CanvasUpdate)
0x0000000039332DB9 (Mono JIT Code) [C:\buildslave\unity\build\Extensions\guisystem\UnityEngine.UI\UI\Core\CanvasUpdateRegistry.cs:151] UnityEngine.UI.CanvasUpdateRegistry:PerformUpdate ()
0x00000000393908AF (Mono JIT Code) (wrapper delegate-invoke) <Module>:invoke_void ()
0x00000000393321CD (Mono JIT Code) [C:\buildslave\unity\build\artifacts\generated\common\modules\UI\UICanvasBindings.gen.cs:240] UnityEngine.Canvas:SendWillRenderCanvases ()
0x000000003939041E (Mono JIT Code) (wrapper runtime-invoke) object:runtime_invoke_void (object,intptr,intptr,intptr)
0x00007FFDE658437A (mono-2.0-bdwgc) [c:\buildslave\mono\build\mono\mini\mini-runtime.c:2620] mono_jit_runtime_invoke
0x00007FFDE6788E87 (mono-2.0-bdwgc) [c:\buildslave\mono\build\mono\metadata\object.c:2853] do_runtime_invoke
0x00007FFDE679188F (mono-2.0-bdwgc) [c:\buildslave\mono\build\mono\metadata\object.c:2905] mono_runtime_invoke
0x0000000140A2EAEC (Unity) scripting_method_invoke
0x0000000140A2243A (Unity) ScriptingInvocation::Invoke
0x00000001417EA826 (Unity) UI::CanvasManager::WillRenderCanvases
0x00000001417EA911 (Unity) `UI::InitializeCanvasManager'::`21'::UIEventsWillRenderCanvasesRegistrator::Forward
0x000000014071F3A1 (Unity) `InitPlayerLoopCallbacks'::`24'::PostLateUpdatePlayerUpdateCanvasesRegistrator::Forward
0x000000014071CE42 (Unity) PlayerLoop
0x00000001411DE245 (Unity) PlayerLoopController::UpdateScene
0x00000001411DF7C8 (Unity) PlayerLoopController::UpdateSceneIfNeeded
0x00000001411E9BDD (Unity) Application::TickTimer
0x000000014140EB0F (Unity) MainMessageLoop
0x00000001414103B5 (Unity) WinMain
0x0000000141E643A8 (Unity) __tmainCRTStartup
0x00007FFE1E3D1FE4 (KERNEL32) BaseThreadInitThunk
0x00007FFE20F3EF91 (ntdll) RtlUserThreadStart