The tools version "15.0" is unrecognized - Incompatible/Unloaded project in Visual Studio 2019 (v16.0.0 Preview 5.0)

I've experienced a similar problem and one entry on ms docs:

https://docs.microsoft.com/en-us/visualstudio/msbuild/updating-an-existing-application?view=vs-2017

has lead me to the answer.

If you ever had any older versions of visual studio installed, prior than 2017 you will have some unwanted dlls installed on the evil gac. You should remove it by using these steps:

1. On poweshell run: gacutil.exe -l | Select-String -Pattern 'Build' | Select-String -Pattern 'Version=15'

2. Remove all found entries. Example:

   gacutil.exe /u "Microsoft.Build.Framework, Version=15.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL"

This will make sure that vs will use it's current version to load the projects. Please note that VS 2019 will always use "Current" and will ignore the ToolsVersion unless you force it to:

https://docs.microsoft.com/en-us/visualstudio/msbuild/overriding-toolsversion-settings?view=vs-2019

OK FIXED THIS ...

My visual studio 2017 MSBuild location:

C:\Program Files (x86)\Microsoft Visual Studio\Enterprise\MSBuild\15.0\Bin

My visual studio 2019 MSBuild location:

C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\MSBuild\15.0\Bin

I noticed that my Visual studio 2019 Bin folder was incomplete so i went on and took a back up (of course) and copied the complete Bin folder from 2017 to 2019.

This fixed everything ... No idea what to say more here, just hopes it can help anyone!

I have had the same exact issues with my attempted upgrade to VS 2019. However, what I have read is that the MSBuild version is supposed to correspond to the Visual Studio version. Hence, VS2017=MSBuild 15.x, VS2019=MSBuild 16.x.

When I installed both VS2019 and MSBuild 16.x at no time did I see in my GAC a build version for 16.x. For both VS2017 and VS2019 installs, the build versions were always at 15.0.

So far, I have had to return to my version of VS2015, which runs all my projects as expected. Not sure what to do since I couldn't get any help from Microsoft technical support without paying $500.00.