Editor Debug is doing a full rebuild every build

Development Platform & Builds Debugging, Optimization, & Profiling
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1

I’m running from github source. I have a project, and when I build it, it does an entire rebuild if I try to work in the debug_editor build target.

I saw that it’s printing this:

------ Build started: Project: myproject, Configuration: Debug_Editor x64 ------
1>Invalidating makefile for myprojectEditor (UE4Editor-Win64-Debug.lib.response modified)

Watching the file and the .old version of the file, here’s what I see:

Whenever I build ‘myproject’, it flips the output of UE4Editor-Win64-Debug.lib.response from this:

/NOLOGO
/errorReport:prompt
/MACHINE:x64
/SUBSYSTEM:WINDOWS
/DEF
/NAME:"UE4Editor-Win64-Debug.exe"
/IGNORE:4221
/NODEFAULTLIB
"C:\Depot\UnrealEngine\Engine\Intermediate\Build\Win64\UE4Editor\Debug\Launch\LaunchWindows.cpp.obj"
"C:\Depot\UnrealEngine\Engine\Intermediate\Build\Win64\UE4Editor\Debug\Launch\Launch.cpp.obj"
"C:\Depot\UnrealEngine\Engine\Intermediate\Build\Win64\UE4Editor\Debug\Launch\LaunchEngineLoop.cpp.obj"
"C:\Depot\UnrealEngine\Engine\Intermediate\Build\Win64\UE4Editor\Debug\Launch\PCLaunch.rc.res"
"C:\Depot\UnrealEngine\Engine\Intermediate\Build\Win64\UE4Editor\Debug\Default.rc2.res"
/OUT:"C:\Depot\UnrealEngine\Engine\Intermediate\Build\Win64\UE4Editor\Debug\UE4Editor-Win64-Debug.lib"

To this:

/NOLOGO
/errorReport:prompt
/MACHINE:x64
/SUBSYSTEM:WINDOWS
/DEF
/NAME:"UE4Editor-Win64-Debug.exe"
/IGNORE:4221
/NODEFAULTLIB
"C:\Depot\UnrealEngine\Engine\Intermediate\Build\Win64\UE4Editor\Debug\Launch\Module.Launch.cpp.obj"
"C:\Depot\UnrealEngine\Engine\Intermediate\Build\Win64\UE4Editor\Debug\Launch\PCLaunch.rc.res"
"C:\Depot\UnrealEngine\Engine\Intermediate\Build\Win64\UE4Editor\Debug\Default.rc2.res"
/OUT:"C:\Depot\UnrealEngine\Engine\Intermediate\Build\Win64\UE4Editor\Debug\UE4Editor-Win64-Debug.lib"

So when I build the “ue4” project, I get the Module.Launch one. But when I build ‘myproject’, suddenly it switches to the LaunchWindows files instead. So it’s changing UE4Editor-Win64-Debug.lib.response constantly, which triggers the full rebuild.

Additionally, if I run the editor build after this, it tells me that the buildId doesn’t match across the modules in ‘myproject’ and the engine (and I’ve verified that they don’t match - it is correct).

So this feels like the ‘Debug Editor’ target has some configuration error for me, and this is as far as I’ve gotten. ‘Development Editor’ works fine, for the record.

2

I believe I have found a solution. I had ‘bUsePDBFiles = true;’ in my personal project’s .uproject file, and when I also added that to UE4Editor.Target.cs file, the issue went away.