Platform Mac is not a valid platform to build. Check that the SDK is installed properly and that you have the necessary platorm support files (DataDrivenPlatformInfo.ini, SDK.json, etc).

Development Programming & Scripting
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1

when creating a new unreal engine project using C++
I encounter this

Setting up bundled DotNet SDK
/Users/Shared/Epic Games/UE_5.4/Engine/Build/BatchFiles/Mac/../../../Binaries/ThirdParty/DotNet/6.0.302/mac-x64
Running dotnet Engine/Binaries/DotNET/UnrealBuildTool/UnrealBuildTool.dll Development Mac -Project=/Users/yahya/Documents/Unreal Projects/MyProject2/MyProject2.uproject -TargetType=Editor -Progress -NoEngineChanges -NoHotReloadFromIDE
Log file: /Users/yahya/Library/Application Support/Epic/UnrealBuildTool/Log.txt
Creating makefile for MyProject2Editor (no existing makefile)
Total execution time: 2.07 seconds
Platform Mac is not a valid platform to build. Check that the SDK is installed properly and that you have the necessary platorm support files (DataDrivenPlatformInfo.ini, SDK.json, etc).
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2

Same with UE 5.6.1 on MacOS 15.6:

Setting up bundled DotNet SDK
/Volumes/Unreal Engine/UE_5.6/Engine/Build/BatchFiles/Mac/../../../Binaries/ThirdParty/DotNet/8.0.300/mac-x64
Running dotnet Engine/Binaries/DotNET/UnrealBuildTool/UnrealBuildTool.dll Development Mac -Project=/Volumes/Unreal Engine/Unreal Projects/MyVehicle/MyVehicle.uproject -TargetType=Editor -Progress -NoEngineChanges -NoHotReloadFromIDE
Log file: /Users/jason/Library/Application Support/Epic/UnrealBuildTool/Log.txt
Creating makefile for MyVehicleEditor (no existing makefile)
Platform Mac is not a valid platform to build. Check that the SDK is installed properly and that you have the necessary platform support files (DataDrivenPlatformInfo.ini, SDK.json, etc).

Result: Failed (OtherCompilationError)
Total execution time: 4.17 seconds
3

The solution was to install Xcode 16.4 alongside Xcode 26 Beta.

If necessary use xcode-select to ensure version 16.4 is the command-line default build tool.

% sudo xcode-select -s /Applications/Xcode.app/Contents/Developer      
Password:
% xcode-select -p
/Applications/Xcode.app/Contents/Developer
1 Like
4

Thanks @RiskNerd! That did it.