Same problem with IVsPackageInstaller.InstallPackage which is not marked as Obsolete. The problem occurs in a custom wizard after adding a new solution with a new project.

IComponentModel componentModel = (IComponentModel)Package.GetGlobalService(typeof(SComponentModel));
IVsPackageInstaller packageInstaller = componentModel.GetService();

packageInstaller.InstallPackage(null, project, package, version, ignoreDependencies: false);

What is the recommended way of adding a PackageReference to a project via EnvDTE?

@JihedHalimi

The comment in this PR for the other API talks about using Microsoft.VisualStudio.OperationProgress to know when the project is ready.
Same recommendation applies to IVsPackageInstaller.

We should add that in the docs for the IVsPackageInstaller/IvsPackageUninstaller.

The problem is that @JihedHalimi said it happens in a "wizard", which I assume means "new project wizard" (template). I don't know how the wizard and project system is implemented, but I wouldn't be surprised if project system doesn't nominate (CPS might not fully load the project?) until after the template wizard finishes. If the wizard is waiting for OperationProgress, then there will be a deadlock.

I think this is a design gap. In any case, it's out of scope for this PR, so it's best to bring up in a new issue in the Home repo.

oh I missed the part about the wizard.

For SDK style projects, you should declare the packages as PackageReference in the project file itself instead of using IVsPackageInstaller.
That's how the SDK based templates that have default packages work.