Msgstr "Target F # Runtime" Gray - Why?

Question

I am trying to change the project target working environment from F # 3.1 to F # 4.0 in RTM VS2015, but the drop-down menu of the target environment is grayed out:

Any reason for this? How can i fix this?

Answer 1

Check the fsproj file, for this you need to specify a link to FSharp.Core, templated by $(TargetFSharpCoreVersion) , for example, <Reference Include="FSharp.Core, Version=$(TargetFSharpCoreVersion), Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" /> .

Some nuget packages break the FSharp.Core template link and replace it with a hard-coded version for a specific package. This prevents the project system from letting you easily switch versions.

To fix this, simply paste it back into the template version.