Description

The package CommunityToolkit.Aspire.Hosting.SqlDatabaseProjects is documented to support .NET 8 and .NET 9, but in practice it only works with .NET 9.
When used in a project targeting .NET 8 (LTS), the Aspire host fails to start with a TypeInitializationException caused by missing MSBuild instance detection.

This issue occurs with all package versions from 9.0.0 to 9.8.0.
Upgrading the entire Aspire solution and all related projects to .NET 9 makes it work, but this is not feasible in enterprise environments where only LTS versions (like .NET 8) are allowed.

💥 Actual Behavior

Application startup fails with the following error:

System.TypeInitializationException: 'The type initializer for 'Aspire.Hosting.SqlProjectBuilderExtensions' threw an exception.'

Inner exception:
System.InvalidOperationException: 'No instances of MSBuild could be detected. 
Try calling RegisterInstance or RegisterMSBuildPath to manually register one.'

⚙️ Environment

💡 Workaround

Migrating the entire solution (Aspire host and projects) to .NET 9 resolves the issue.
However, this is not viable for enterprise environments restricted to LTS (.NET 8) releases.

Regression

No response

🔄 Reproduction Steps

1. Create a new Aspire project targeting .NET 8 (e.g., Aspire version 9.5.1).

2. Add the following package:

<PackageReference Include="CommunityToolkit.Aspire.Hosting.SqlDatabaseProjects" Version="9.8.0" />


3. In Program.cs, add the following code:

var builder = DistributedApplication.CreateBuilder(args);

var sql = builder.AddSqlServer("sql")
    .WithLifetime(ContainerLifetime.Persistent)
    .WithDataVolume();

var sqlDb = sql.AddDatabase("db");
builder.AddSqlProject<Projects.sql_db_prj>("sql-db-project")
       .WithReference(sqlDb);

4. Run the Aspire host.

✅ Expected Behavior

The SQL project should load and register correctly in Aspire when running under .NET 8, without requiring migration to .NET 9.

Screenshots

No response

IDE and version

VS 2022

IDE version

17.14.18

Nuget packages

CommunityToolkit.Aspire.Hosting.SqlDatabaseProjects 9.8.0

🧩 Additional Context

It seems the MSBuildLocator used by the SqlProjectBuilderExtensions class is unable to detect MSBuild instances when running under .NET 8.
This might be related to the internal version checks or SDK references baked into the package build.

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