publishsinglefile causes runtime failure of hostpolicy.dll not found for dotnet 9.0.100

[jsahaj]

HelloWorldExample1.zip
When doing publishsinglefile=true and running resulting exe we get a runtime failure of hostpolicy.dll not found for dotnet 9.0.100. This is a regression from net8, where it builds and runs fine.

With C# project file is defined as:
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType> <TargetFramework>net8.0</TargetFramework> <ImplicitUsings>enable</ImplicitUsings> <Nullable>enable</Nullable> <PlatformTarget>x64</PlatformTarget> <PublishSingleFile>true</PublishSingleFile> <SelfContained>true</SelfContained> <PublishTrimmed>true</PublishTrimmed> <RuntimeIdentifier>win-x64</RuntimeIdentifier> </PropertyGroup>

<Target Name="PostBuild" AfterTargets="PostBuildEvent">
<Exec Command="dotnet publish --configuration $(Configuration) --runtime win-x64 --self-contained true -p:PublishSingleFile=true -p:PublishTrimmed=true --no-build --output=$(EXEOUT) HelloWorldExample1.csproj" />
</Target>
</Project>

Set EXEOUT to some directory and build the project. Go to exeout directory at command prompt and run the executable and to get error:

c:\Temp\exeout>HelloWorldExample1.exe
A fatal error was encountered. The library 'hostpolicy.dll' required to execute the application was not found in 'C:\Program Files\dotnet'.
Failed to run as a self-contained app.

• The application was run as a self-contained app because 'c:\Temp\exeout\HelloWorldExample1.runtimeconfig.json' was not found.
• If this should be a framework-dependent app, add the 'c:\Temp\exeout\HelloWorldExample1.runtimeconfig.json' file and specify the appropriate framework.

Removing the publishsinglefile allows program to run without error.

Versions:
dotnet 9.0.100
VS 17.12.1
csc 4.12.0-3.24558.5