Project file has no matching compilation unit

1. What happened
The following error is thrown:
NotSupportedException: Visual Studio Tools: Project file has no matching compilation unit for <AssemblyName xmlns="http://schemas.microsoft.com/developer/msbuild/2003">

2. How we can reproduce it using the example you attached
1. Create new empty Unity3D 2018.2.0f2 project
2. Exit unity and find the project folder in windows explorer
3. Create a new folder under Packages called com.test.compilationunit
4. Add a package.json to this folder that contains:
{
"name": "com.test.compilationunit",
"displayName": "no matching compilation unit",
"version": "0.0.1",
"unity": "2018.2",
"description": "Try to repo project file has no matching compilation unit for.",
"dependencies": { }
}
5. Add a PackageComponent.cs to this folder that contains:
using UnityEngine; public class PackageComponent : MonoBehaviour {}

6. Load this project in Unity
Observe: Package "no matching compilation unit" has loaded without errors

7. Add a UsePackage.cs to the projects Assets folder that contains:
public class UsePackage : PackageComponent {}

8. Give the unity editor focus so it rebuilds
Observe: no errors

9. Exit Unity
10. Move the folder you created in step #3 to somewhere else, maybe C:\com.test.compilationunit
11. Update the projects manifest.json to include the new package location
{
"dependencies": {
"com.test.compilationunit": "file:C:\\com.test.compilationunit",
"com.unity.ads": "2.0.8",

12. Load the project in Unity

Expected: the package to still load without errors
Observe: the package has the error NotSupportedException: Visual Studio Tools: Project file has no matching compilation unit for <AssemblyName xmlns="http://schemas.microsoft.com/developer/msbuild/2003">

Solution:
Please install these 2 updates from Microsoft:
https://xamarin.azureedge.net/vstu/dev15/3.8.0.3/vstu2017.msi
https://xamarin.azureedge.net/vstu/dev15/3.8.0.3/SyntaxTree.VisualStudio.Unity.vsix