EF Core + SQL Server causes Roslyn error in .NET 9 project when used with Carter

[TanerSaydam]

Summary

When I add EF Core (with SQL Server and Tools) to a .NET 9 project using Carter, I receive a Roslyn-related error when trying to run the application or generate migrations using Code First.

However, when I use only Microsoft.EntityFrameworkCore.InMemory, everything works fine.

Reproduction Steps

1. Create a new .NET 9 minimal API project.
2. Add Carter.
3. Add the following packages:
   • Microsoft.EntityFrameworkCore.SqlServer (tried both 9.0.7 and 9.0.0)
   • Microsoft.EntityFrameworkCore.Tools
4. Try to run the project or execute dotnet ef migrations add InitialCreate.

Error Output

Unable to load one or more of the requested types.
Method 'get_IsParamsArray' in type 'Microsoft.CodeAnalysis.CodeGeneration.CodeGenerationParameterSymbol' from assembly 'Microsoft.CodeAnalysis.Workspaces, Version=4.8.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' does not have an implementation.
Method 'get_PartialDefinitionPart' in type 'Microsoft.CodeAnalysis.CodeGeneration.CodeGenerationPropertySymbol' from assembly 'Microsoft.CodeAnalysis.Workspaces, Version=4.8.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' does not have an implementation.
Method 'get_AllowsRefLikeType' in type 'Microsoft.CodeAnalysis.CodeGeneration.CodeGenerationTypeParameterSymbol' from assembly 'Microsoft.CodeAnalysis.Workspaces, Version=4.8.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' does not have an implementation.

[jchannon]

Please try this #369 (comment)

…

On Sat, 19 Jul 2025 at 16:15, Taner Saydam ***@***.***> wrote: *TanerSaydam* created an issue (CarterCommunity/Carter#377) <#377> Summary When I add EF Core (with SQL Server and Tools) to a .NET 9 project using Carter, I receive a Roslyn-related error when trying to run the application or generate migrations using Code First. However, when I use only Microsoft.EntityFrameworkCore.InMemory, everything works fine. Reproduction Steps 1. Create a new .NET 9 minimal API project. 2. Add Carter. 3. Add the following packages: - Microsoft.EntityFrameworkCore.SqlServer (tried both 9.0.7 and 9.0.0) - Microsoft.EntityFrameworkCore.Tools 4. Try to run the project or execute dotnet ef migrations add InitialCreate. Error Output Unable to load one or more of the requested types. Method 'get_IsParamsArray' in type 'Microsoft.CodeAnalysis.CodeGeneration.CodeGenerationParameterSymbol' from assembly 'Microsoft.CodeAnalysis.Workspaces, Version=4.8.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' does not have an implementation. Method 'get_PartialDefinitionPart' in type 'Microsoft.CodeAnalysis.CodeGeneration.CodeGenerationPropertySymbol' from assembly 'Microsoft.CodeAnalysis.Workspaces, Version=4.8.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' does not have an implementation. Method 'get_AllowsRefLikeType' in type 'Microsoft.CodeAnalysis.CodeGeneration.CodeGenerationTypeParameterSymbol' from assembly 'Microsoft.CodeAnalysis.Workspaces, Version=4.8.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' does not have an implementation. — Reply to this email directly, view it on GitHub <#377>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAZVJWOOZGEERAD7C6DDAL3JJOI5AVCNFSM6AAAAACB4XAJKCVHI2DSMVQWIX3LMV43ASLTON2WKOZTGI2DKMZXGUYTEMI> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>