Just wondering if anyone has seen this error before - “UnrealBuildTool : error : Unable to merge actions producing BuildingGenerator.cpp.obj: prerequisites are different”. I’m not really sure what I’ve done but i can no longer build my project. I was playing around with git before hand however before i did that i backed up the project to another disk, I’ve since tried to restore it from the disk backup and still no luck.
One issue I was having before this is I was unable to open a source file in Visual Studio. I tracked it down to a byte with hex value 0b. Removing these bytes I then get this unable to merge actions error. When i try to compile with these bytes in the source file I get an error regarding unable to find a header file from the project (which is definitely where it’s specified).
edit - added full error list and log contents
The full error list is:
1>UnrealBuildTool : error : Unable to merge actions producing BuildingGenerator.cpp.obj: prerequisites are different
1>UnrealBuildTool : error : Unable to merge actions producing BuildingGenerator.cpp.obj: prerequisites are different
1>UnrealBuildTool : error : Action graph is invalid; unable to continue. See log for additional details.
In the log file i found under \Engine\Programs\UnrealBuildTool contains the following
Action.LogConflict: UnrealBuildTool: ERROR: Unable to merge actions producing BuildingGenerator.cpp.obj: prerequisites are different
Action.LogConflict: Previous: [Project Dir]\Source\My_Project\BuildingGenerator.cpp, [Project Dir]\Intermediate\Build\Win64\UE4Editor\DebugGame\My_Project\PCH.My_Project.h.pch, [Project Dir]\Intermediate\Build\Win64\UE4Editor\DebugGame\My_Project\BuildingGenerator.cpp.obj.response
Action.CheckForConflicts: Conflict: [Project Dir]\Source\My_Project\BuildingGenerator\BuildingGenerator.cpp, [Project Dir]\Intermediate\Build\Win64\UE4Editor\DebugGame\My_Project\PCH.My_Project.h.pch, [Project Dir]\Intermediate\Build\Win64\UE4Editor\DebugGame\My_Project\BuildingGenerator.cpp.obj.response
Action.LogConflict: UnrealBuildTool: ERROR: Unable to merge actions producing BuildingGenerator.cpp.obj: prerequisites are different
Action.LogConflict: Previous: [Project Dir]\Source\My_Project\BuildingGenerator.cpp, [Project Dir]\Intermediate\Build\Win64\UE4Editor\DebugGame\My_Project\PCH.My_Project.h.pch, [Project Dir]\Intermediate\Build\Win64\UE4Editor\DebugGame\My_Project\BuildingGenerator.cpp.obj.response
Action.CheckForConflicts: Conflict: [Project Dir]\Source\My_Project\BuildingGenerator\BuildingGenerator.cpp, [Project Dir]\Intermediate\Build\Win64\UE4Editor\DebugGame\My_Project\PCH.My_Project.h.pch, [Project Dir]\Intermediate\Build\Win64\UE4Editor\DebugGame\My_Project\BuildingGenerator.cpp.obj.response
UnrealBuildTool.Main: UnrealBuildTool: ERROR: Action graph is invalid; unable to continue. See log for additional details.
UnrealBuildTool.Main: BuildException: Action graph is invalid; unable to continue. See log for additional details.
UnrealBuildTool.Main: at UnrealBuildTool.ActionGraph.CheckForConflicts(IEnumerable`1 Actions) in D:\UE4\UnrealEngine-release\Engine\Source\Programs\UnrealBuildTool\System\ActionGraph.cs:line 81
UnrealBuildTool.Main: at UnrealBuildTool.BuildMode.Build(List`1 TargetDescriptors, BuildConfiguration BuildConfiguration, ISourceFileWorkingSet WorkingSet, BuildOptions Options) in D:\UE4\UnrealEngine-release\Engine\Source\Programs\UnrealBuildTool\Modes\BuildMode.cs:line 236
UnrealBuildTool.Main: at UnrealBuildTool.BuildMode.Execute(CommandLineArguments Arguments) in D:\UE4\UnrealEngine-release\Engine\Source\Programs\UnrealBuildTool\Modes\BuildMode.cs:line 191
UnrealBuildTool.Main: at UnrealBuildTool.UnrealBuildTool.Main(String[] ArgumentsArray) in D:\UE4\UnrealEngine-release\Engine\Source\Programs\UnrealBuildTool\UnrealBuildTool.cs:line 443