How do I debug this compile error? FileNotFoundException [ProjectName]-7371.dll.response

I am not sure how to debug this compile error. It started popping up when adding an character that uses an AI Controller. VS builds the project without error.

Info Compiling game modules for hot reload
Info ERROR: System.IO.FileNotFoundException: Could not find file 'D:\Dropbox\Dev\ProjectName\Intermediate\Build\Win64\ProjectName\Development\UE4Editor-ProjectName-7371.dll.response'.
Info File name: 'D:\Dropbox\Dev\TopShelfHockey\Intermediate\Build\Win64\ProjectName\Development\UE4Editor-ProjectName-7371.dll.response'
Info    at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
Info    at System.IO.File.InternalCopy(String sourceFileName, String destFileName, Boolean overwrite, Boolean checkHost)
Info    at UnrealBuildTool.UnrealBuildTool.PatchActionHistoryForHotReloadAssembling(List`1 OnlyModules)
Info    at UnrealBuildTool.UnrealBuildTool.RunUBT(String[] Arguments)

This is UBT crash, he trying to do something with hot reload, try rebuilding code without editor turned on, maybe it will fix itself that way

Unfortunately that did not help, I opened it directly in VS, cleaned and rebuilt. Opened the editor, saved, compiled and it failed, same error. :confused:

Got the same problem today on UE 4.9.1. Dont know how to debug it, but renaming similar file in this directory helps:
ProjectName\Intermediate\Build\Win64\ProjectName\Development\UE4Editor-ProjectName.dll.response

to

ProjectName\Intermediate\Build\Win64\ProjectName\Development\UE4Editor-ProjectName-7371.dll.response

(where “7371” may be different number, check error log)