"error FS0193: internal error: Value cannot be null. Parameter name: con"

[bentayloruk]

I wasn't sure whether to add this as a comment to #20. Figured new issue would be best.

I'm getting "error FS0193: internal error: Value cannot be null. Parameter name: con" when running the simple build script below. This script works with FAKE 1.64.7 but fails with the error on the latest -pre version FAKE.2.1.155-alpha.

Any suggestions you might have on how to resolve/diagnose this would be great. If you need more information, please tell me what you need. Thanks.

#I @".\src\packages\FAKE.2.1.155-alpha\tools"
#r @".\src\packages\FAKE.2.1.155-alpha\tools\FakeLib.dll"
open System
open Fake

let version = "0.1.0"
let buildOutputPath = @".\build\output"
let buildDirs = [ buildOutputPath; ]

let projFiles =
    !+ @".\src\**\*.csproj"
    -- @".\src\**\*Tests.csproj"
    |> Scan

Target "Clean" (fun _ -> CleanDirs buildDirs)

//Build
Target "BuildProjects" (fun _ ->
    MSBuild buildOutputPath "Build" ["Configuration", "Release"]  projFiles
    |> Log "BuildOutput:"
)


"Clean"
    ==> "BuildProjects" 

Run "BuildProjects" 

[colinbull]

Is this running through FSI or the command line? i.e Fake.exe

[bentayloruk]

I'm calling "fsi build.fsx" from a batch file that I invoke from the
command line.

[colinbull]

Ahh.. Ok try running it using Fake.exe instead,

"src\packages\FAKE.2.1.155-alpha\tools\fake.exe" "build.fsx"
pause

I get an error using fsi.exe, albeit a different one. I'll continue to have a play and see if I can get the same error. Let me know whether the above works.

[bentayloruk]

Thanks for your help with this Colin. That seems to work. Is using Fake.exe the recommended approach now? I don't think that existed when I wrote my build scripts. Can't see anything about it in the docs.

[bentayloruk]

Odd. I have made this change on a slightly more complex version of build.fsx and the Nuget task (that works on 1.64.7) now complains that "The directory is invalid" for the nuget.exe path. Different problem, but seemingly a change between versions. I'm gonna get setup for some debugging here.

[colinbull]

Yeah, I'm pretty sure Fake.exe is the recommended way of doing this as it sets up the environment a little better. As for the nuget stuff I'm not sure, but you might want to try things like removing trailing slashes from the tool path if you are not using the default ./tools/NuGet/NuGet.exe