MissingMethodException when trying to print a string in F#
Hi,
When I try to do a basic printfn call in F#, I get a MissingMethodException: Method not found: 'Void Microsoft.FSharp.Core.PrintfFormat`5..ctor(System.String)'.
The code to repro is simple:
printfn "%s" "Hi"
Any ideas on how to fix this?
Thanks,
Jon
Environment:
LINQPad 6.5.5 (x64)
Windows 10
VS 2019 16.4.1
❯ dotnet --list-sdks
1.1.8 [C:\Program Files\dotnet\sdk]
2.2.109 [C:\Program Files\dotnet\sdk]
2.2.402 [C:\Program Files\dotnet\sdk]
3.0.101 [C:\Program Files\dotnet\sdk]
3.1.100 [C:\Program Files\dotnet\sdk]
Comments
You're probably missing the reference assemblies. Click the exclamation mark in the toolbar to restore.
That fixed it. Thanks!
Hi, would you be able to point out what assemblies need to be referenced to fix this, exactly? I'm getting this exact error in some code I compile without LINQPad, running fsc.exe in my own application. Microsoft.FSharp.Core.PrintfFormat is, of course, defined in FSharp.Core.dll, which I'm already referencing.
You need the reference assemblies for the runtime that you're using (.NET 3.1 or .NET 5). If you have the SDK installed, they are located in %programfiles%\dotnet\packs\Microsoft.NETCore.App.Ref\5.0.0\ref\net5.0. If you don't have the SDK, you can download them from the Microsoft.NETCore.App.Ref NuGet package. I don't know whether fsc.exe has an option to help you with this.
Your other option is to use dotnet build - I believe this is the recommended solution outside Visual Studio and LINQPad.
Using the reference assemblies worked, thank you so much! It was a little trickier than that, because they are sometimes in %ProgramFiles% and sometimes a NuGet package for some reason (even though I do have the SDK).