Cannot find reference System

Question

So I use Visual Studio 2017 and everything worked ok. But then I updated to 15.6.0 and suddenly nothing is working anymore.

All the references like Systme.* or Microsoft.* are with a yellow warning sign...

At every project - even new ones- I keep getting the same type of erros after (re)building:

The "ResolveAssemblyReference" task could not be initialized with its input parameters

The "ResolveAssemblyReference" task could not be initialized with its input parameters      

The "FindDependenciesOfExternallyResolvedReferences" parameter is not supported by the "ResolveAssemblyReference" task. Verify the parameter exists on the task, and it is a settable public instance property          

This project references NuGet package(s) that are missing on this computer. Use NuGet Package Restore to download them

I have tried reinstalling Visual Studio 2017, reinstalling .NET Framework, but I still get these type of errors on every C# project...

Is there any solution, next to completely reinstalling Windows?

Answer 1

Community edit (Nick's comment below - an important warning):

It is dangerous and totally unsupported to overwrite parts of MSBuild 15.6 with parts of MSBuild 15.5. All sorts of other things could break.

---

Finally fixed it!

This file got corrupted somehow through the update to 15.6.0:

C:\Program Files (x86)\Microsoft Visual Studio\2017\EnterpriseWMSBuild\15.0\bin\Microsoft.Common.CurrentVersion.targets

or

C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\15.0\Bin\Microsoft.Common.CurrentVersion.targets

Replace that file with the previous version, and that fixed all the errors!

Get the previous version from a co-worker who hasn't updated their Visual Studio yet.