Builds against target framework net35/net40 fail with the VS16.5 update -- Cannot read or write file Fsharp.Core.dll #8739
Description
Builds of F# projects against target framework net35 fail with the VS16.5 update. This happens with both old-style long-form projects or the new lightweight ones.
Repro steps
The simplest repro is
- dotnet new classlib -lang F#
- edit project as follows to target .Net Framework 3.5
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>net35</TargetFramework>
</PropertyGroup>
<ItemGroup>
<Compile Include="Library.fs" />
</ItemGroup>
<ItemGroup>
<PackageReference Update="FSharp.Core" Version="3.0.2" />
</ItemGroup>
</Project>
- dotnet restore
- msbuild [project]
Expected behavior
Trivial compilation just works
Actual behavior
"C:\Users\steve\Documents\scratch\scratch.fsproj" (default target) (1) ->
(CoreCompile target) ->
FSC : error FS0229: Error opening binary file 'C:\Users\steve\.nuget\packages\fsharp.core\3.0.2\lib\net35\FSharp.Core .dll': Cannot read or write file [C:\Users\steve\Documents\sscratch\scratch.fsproj]
FSC : error FS3160: Problem reading assembly 'C:\Users\steve\.nuget\packages\fsharp.core\3.0.2\lib\net35\FSharp.Core. dll': The exception has been reported. This internal exception should now be caught at an error recovery point on the stack. Original message: Error opening binary file 'C:\Users\steve\.nuget\packages\fsharp.core\3.0.2\lib\net35\FSharp.Co re.dll': Cannot read or write file) [C:\Users\steve\Documents\scratch\scratch.fsproj]
error FS0073 : internal error : BuildFrameworkTcImports: no successful import of C:\Users\steve\.nuget\packages\fshar p.core\3.0.2\lib\net35\FSharp.Core.dll [C:\Users\steve\Documents\scratch\scratch.fsproj]
Known workarounds
Using an older compiler version
Related information
Windows 10 Home build 1909
Visual Studio 16.5