Frequent crash occurs once when building lighting after editing a landscape. I added components to the landscape, sculpted, and flattened it.
I wasn't able to reproduce the issue again, so the above repro is what I was doing leading up to the crash.
RESULT
Crash
UE4Editor_Engine!FShaderCompilingManager::PropagateMaterialChangesToPrimitives() shadercompiler.cpp:1910
UE4Editor_Engine!FShaderCompilingManager::ProcessCompiledShaderMaps() shadercompiler.cpp:1874
UE4Editor_Engine!FShaderCompilingManager::ProcessAsyncResults() shadercompiler.cpp:2328
UE4Editor!FEngineLoop::Tick() launchengineloop.cpp:3028
UE4Editor!GuardedMain() launch.cpp:166
UE4Editor!GuardedMainWrapper() launchwindows.cpp:130
UE4Editor!WinMain() launchwindows.cpp:206
UE4Editor!__scrt_common_main_seh() exe_common.inl:264
kernel32!<Unknown>
ntdll!<Unknown>
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-39977 in the post.