[CrashReport] UE4Editor-Renderer.dylib!FSceneRenderTargets::GetGBufferResourcesUniformBuffer()

Assertion failed: Assertion failed: IsValidRef(GBufferResourcesUniformBuffer) [File:Runtime/Renderer/Private/PostProcess/SceneRenderTargets.h] [Line: 436] 
GBuffer required but not available. Failure often caused by incorrect custom code use in a post processing material.

LogCrashTracker: 

LogMac: === Critical error: ===
SIGSEGV: invalid attempt to access memory at address 0x3

LogMac: FGenericPlatformMisc::RaiseException(unsigned int) Address = 0x5f9c00b  (filename not found) [in UE4Editor-Core.dylib]
FOutputDeviceMacError::Serialize(wchar_t const*, ELogVerbosity::Type, FName const&) Address = 0x6197a2f  (filename not found) [in UE4Editor-Core.dylib]
FOutputDevice::Logf(wchar_t const*, ...) Address = 0x62786cd  (filename not found) [in UE4Editor-Core.dylib]
FDebug::AssertFailed(char const*, char const*, int, wchar_t const*, ...) Address = 0x61de93e  (filename not found) [in UE4Editor-Core.dylib]
FSceneRenderTargets::GetGBufferResourcesUniformBuffer() const Address = 0x1692dfc2 (filename not found) [in UE4Editor-Renderer.dylib]
void FDeferredPixelShaderParameters::Set<FRHIPixelShader*, FRHICommandList>(FRHICommandList&, FRHIPixelShader*, FSceneView const&, EMaterialDomain, ESceneRenderTargetsMode::Type) const Address = 0x16933713 (filename not found) [in UE4Editor-Renderer.dylib]
...

UE4Editor-Renderer.dylib!FSceneRenderTargets::GetGBufferResourcesUniformBuffer()
UE4Editor-Renderer.dylib!void FDeferredPixelShaderParameters::Set<FRHIPixelShader*, FRHICommandList>()
UE4Editor-Renderer.dylib!void FMaterialShader::SetParameters<FRHIPixelShader*>()
UE4Editor-Renderer.dylib!FRCPassPostProcessMaterial::Process()
UE4Editor-Renderer.dylib!FRenderingCompositionGraph::RecursivelyProcess()
UE4Editor-Renderer.dylib!FRenderingCompositePassContext::Process()
UE4Editor-Renderer.dylib!FPostProcessing::Process()
UE4Editor-Renderer.dylib!FDeferredShadingSceneRenderer::Render()
UE4Editor-Renderer.dylib!FRendererModule::BeginRenderingViewFamily(FCanvas*, FSceneViewFamily*)::EURCMacro_FDrawSceneCommand::DoTask()
UE4Editor-Renderer.dylib!TGraphTask<FRendererModule::BeginRenderingViewFamily(FCanvas*, FSceneViewFamily*)::EURCMacro_FDrawSceneCommand>::ExecuteTask()
UE4Editor-Core.dylib!FNamedTaskThread::ProcessTasksNamedThread()
UE4Editor-Core.dylib!FNamedTaskThread::ProcessTasksUntilQuit()
UE4Editor-Core.dylib!FTaskGraphImplementation::ProcessThreadUntilRequestReturn()
UE4Editor-RenderCore.dylib!RenderingThreadMain()
UE4Editor-RenderCore.dylib!FRenderingThread::Run()
UE4Editor-Core.dylib!FRunnableThreadPThread::Run()
UE4Editor-Core.dylib!FRunnableThreadPThread::_ThreadProc()
libsystem_pthread.dylib!<Unknown>
libsystem_pthread.dylib!<Unknown>
libsystem_pthread.dylib!<Unknown>