Assets file obj\project.assets.json doesn't have a target - VS2017

According to the Microsoft blog (which, bizarrely, my account doesn't have permissions to post in), this isn't a bug, and is entirely caused by ReSharper. If you disable this, the problem goes away.

Errr, one problem: I'm getting this error, and I don't have ReSharper.

After a lot of hunting around, I found the reason I was getting the error on my .NET Core project which had been upgraded from 1.0 to 2.1.

When running my project in Debug or Release mode, everything worked fine, but when I tried to publish to Azure, I got that error:

Assets file '(mikesproject)\obj\project.assets.json' doesn't have a target for '.NETCoreApp,Version=v2.0'. Ensure that restore has run and that you have included 'netcoreapp2.0' in the TargetFrameworks for your project.

Although I had updated the version of .NET Core to 2.1 in Project\Properties and upgraded the various nuget packages, there was one place which hadn't picked up this change... the Publish Profile file.

I needed to go into the Properties\PublishProfiles folder in my solution, open up the .pubxml file relating to the way I was publishing to Azure, and change this setting from netcoreapp2.0 to netcoreapp2.1:

<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup>
    . . . 
    <TargetFramework>netcoreapp2.0</TargetFramework>
    . . . 
  </PropertyGroup>
</Project>

Ridiculous, hey?

I do wish Microsoft error messages gave some clue as to the source of problems like this.

Restarting Visual Studio solved the error for me.

Right click on the project file, and click unload. Then right click on the project and reload.