After updating visual studio to version 16.8.2, my solution which uses Post Sharp no longer builds. I didn't upgrade any projects to use .Net 5. Here are the errors I'm seeing:
Severity Code Description Project File Line Suppression State
Error CS0006 Metadata file 'C:\Dev\repos\hinge\HingeSolution\HingeApi\bin\Debug\netcoreapp3.1\HingeApi.dll' could not be found HingeApi-tests C:\Dev\repos\hinge\HingeSolution\HingeApi-tests\CSC 1 N/A
Error MSB4064 The "RuntimeGraphPath" parameter is not supported by the "PrepareForReadyToRunCompilation" task. Verify the parameter exists on the task, and it is a settable public instance property. HingeApi C:\ProgramData\PostSharp\CrossGenPaths\sdk5.0.100-netcoreapp5.0-r5.0.0-win-x64\CrossGen.proj 11
Error MSB4063 The "PrepareForReadyToRunCompilation" task could not be initialized with its input parameters. HingeApi C:\ProgramData\PostSharp\CrossGenPaths\sdk5.0.100-netcoreapp5.0-r5.0.0-win-x64\CrossGen.proj 11
Error The process "dotnet" failed with exit code 1. HingeApi C:\Users\dbdav.nuget\packages\postsharp\6.5.4\build\PostSharp.targets 381
Error error: Unhandled exception (PostSharp.Compiler.Hosting.CommandLine.dll 6.5.4 release | .NET Core 5.0.0 (X64)): Value cannot be null or an empty string. (Parameter 'value') See below for details. HingeApi C:\Dev\repos\hinge\HingeSolution\HingeApi\POSTSHARP 1
Error System.ArgumentException: Value cannot be null or an empty string. (Parameter 'value') HingeApi C:\Dev\repos\hinge\HingeSolution\HingeApi\POSTSHARP 1
Error at NuGet.Versioning.NuGetVersion.Parse(String value) HingeApi C:\Dev\repos\hinge\HingeSolution\HingeApi\POSTSHARP 1
Error at PostSharp.Sdk.Extensibility.PlatformContext.^TTQPa/Ij() in ^f/gziTthOsZk:line 354 HingeApi C:\Dev\repos\hinge\HingeSolution\HingeApi\POSTSHARP 1
Error at PostSharp.Sdk.Extensibility.PlatformContext.^pFnf8wEt() in ^f/gziTthOsZk:line 114 HingeApi C:\Dev\repos\hinge\HingeSolution\HingeApi\POSTSHARP 1
Error at PostSharp.Sdk.Extensibility.Project.^pFnf8wEt(ProjectConfiguration[] _0, ProjectInvocationParameters _1) in ^hW2eIAWj:line 795 HingeApi C:\Dev\repos\hinge\HingeSolution\HingeApi\POSTSHARP 1
Error at PostSharp.Sdk.Extensibility.Project.^pFnf8wEt(ProjectInvocationParameters _0) in ^hW2eIAWj:line 570 HingeApi C:\Dev\repos\hinge\HingeSolution\HingeApi\POSTSHARP 1
Error at PostSharp.Sdk.Extensibility.Project.LoadProject(ProjectInvocationParameters projectInvocationParameters, Domain& domain) in ^hW2eIAWj:line 541 HingeApi C:\Dev\repos\hinge\HingeSolution\HingeApi\POSTSHARP 1
Error at PostSharp.Hosting.PostSharpObject.InvokeProject(ProjectInvocation projectInvocation) in C:\src\PostSharp-65\Public\Core\PostSharp.Compiler.Hosting\PostSharpObject.cs:line 256 HingeApi C:\Dev\repos\hinge\HingeSolution\HingeApi\POSTSHARP 1
Error at PostSharp.Hosting.Program.ExecuteImpl() in C:\src\PostSharp-65\Public\Core\PostSharp.Compiler.Hosting\Program.cs:line 957 HingeApi C:\Dev\repos\hinge\HingeSolution\HingeApi\POSTSHARP 1
I have tried rebuild, clean and build. Has anyone out there overcome this issue?
PostSharp 6.7 is not compatible with .NET 5.0 SDK due to MSBuild changes. .NET 5.0 SDK is installed by Visual Studio Installer when upgrading to VS 16.8.
You can either stay on 3.1 SDK using global.json or use PostSharp 6.8. It's still in preview, but the RC should be released soon.
More information is available here.
EDIT: Postsharp 6.8 RC was released.