from UE_5.3 to UE_5.6 -> can't compile old project

Development Platform & Builds
1

Hi,
when i compile i get the error:

C\ProgramFiles\EpicGames\UE_5.6\Engine\Source\Runtime\CoreUObject\Public\UObject\UObjectGlobals.h(738,33): error C3615: function constexpr ‘FLoadPackageAsyncProgressDelegate::BuildMask’ cannot contain const expression

chatGPT told me it was about MSCV 14.38 which didn’t support some c++20 new feature …
so i managed to generate my .uproject with last version MSCV 14.44 … by rebuilding UnrealBuildTool.dll, bypassing the exception that blocks versions 14.39+
But i still got the compiling error.
chatGPT made me verify eveything, .NET installs, right compiler version etc … but ended up (after 6 hours) telling me it was pointless unless i recompile the unreal myself … which i don’t want to do.

Has anyone successfully compiled a 5.6 project?
I find it weird that noone else has this, even with fresh installs (UE + VS2022)

Did anyone even encounter this?

2

Do not complicate yourself just do this, and do not use the latest Windows 1 1 SDK . I use Windows 10 SDK 10.0.20348.0

Capture
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3

doesn’t work

4

and ofc, compilation bug isn’t there on am empty new project …
what are my non-nightmarish solutions?

5

well in 5.6, c++ version goes from v17 to v20, and there is quite some changes.
i solved it by adding this line in ''ProjectNameEditor.target.cs":
WindowsPlatform.bStrictConformanceMode = true;