The SDK 'Aspire.AppHost.Sdk/9.0.0' specified could not be found

Question

After installing Visual Studio Community 2022 to version 17.12.3 and installed the .NET 9.0 Runtime, every time I try to create a new .NET Aspire Starter App project or try to add Aspire to an existing project using the .NET Aspire Orchestration support option, I get the following error message:

The SDK 'Aspire.AppHost.Sdk/9.0.0' specified could not be found.
D:\Project\AspireApp\AspireApp.AppHost\AppHost.csproj

I've validated through the Visual Studio Installer that both the .NET Aspire SDK and .NET SDK are installed

I did have .NET Aspire8 installed previously through the .NET workload but uninstalled it thinking that would solve the issue.

Dotnet Info:

PS C:\Windows\system32> dotnet --info
.NET SDK:
 Version:           9.0.101
 Commit:            eedb237549
 Workload version:  9.0.100-manifests.4a280210
 MSBuild version:   17.12.12+1cce77968

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19045
 OS Platform: Windows
 RID:         win-x64
 Base Path:   C:\Program Files\dotnet\sdk\9.0.101\

.NET workloads installed:
 [aspire]
   Installation Source: VS 17.12.35527.113
   Manifest Version:    8.2.2/8.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.aspire\8.2.2\WorkloadManifest.json
   Install Type:              Msi

Configured to use loose manifests when installing new manifests.

Host:
  Version:      9.0.0
  Architecture: x64
  Commit:       9d5a6a9aa4

.NET SDKs installed:
  9.0.101 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 8.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 9.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 8.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 9.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 8.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 9.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
  x86   [C:\Program Files (x86)\dotnet]
    registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
  Not set

global.json file:
  Not found

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download

The things I've tried so far:

• Restarting machine (multiple times)
• Validated AppHost project is referencing the correct SDK version
• Uninstall Aspire .NET 8 SDK from the .NET workloads
• Running Visual Studio repair
• Uninstalling .NET 9 Runtime and Aspire SDK and reinstalling using Visual Studio installer
• Validating and moving C:\Program Files\dotnet\ path in environment variables so it's above the x86 path.
• Completely uninstalled Visual Studio and all .NET runtimes from the machine. Reinstalled the latest version of Visual Studio Community.

Here is the project file for the AppHost project

<Project Sdk="Microsoft.NET.Sdk">

  <Sdk Name="Aspire.AppHost.Sdk" Version="9.0.0" />

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net9.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <IsAspireHost>true</IsAspireHost>
    <UserSecretsId>27eb1e38-2d85-47ae-9ba0-d59db5b4e75c</UserSecretsId>
  </PropertyGroup>

  <ItemGroup>
    <ProjectReference Include="..\AspireApp.ApiService\AspireApp.ApiService.csproj" />
    <ProjectReference Include="..\AspireApp.Web\AspireApp.Web.csproj" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="Aspire.Hosting.AppHost" Version="9.0.0" />
  </ItemGroup>

</Project>

Anyone have any suggestions or know how to fix this issue?

Answer 1

I had this issue as well and solved it by adding a package source in visual studio like this:

Once added, I closed Visual Studio and created a new Aspire project with no error message.