What will cause HotReload to fail ?

In my case, CSV_DEFINE_CATEGORY in one of the game modules will give below messages:

LogWindows: Windows GetLastError: The operation completed successfully. (0)
LogWindows: Failed to load 'D:/Code/FigureOut/zhihu_xuanran_sjuan2/Binaries/Win64/UE4Editor-DirGravity-7930.dll' (GetLastError=1114)
LogModuleManager: Warning: ModuleManager: Unable to load module 'D:/Code/FigureOut/zhihu_xuanran_sjuan2/Binaries/Win64/UE4Editor-DirGravity-7930.dll' because the file couldn't be            loaded by the OS.
Warning: HotReload failed, reload failed /Script/DirGravity.
LogContentBrowser: Native class hierarchy populated in 0.0099 sec

Does anyone know why?