## 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.
Please try this
https://github.com/CarterCommunity/Carter/issues/369#issuecomment-2806286819
On Sat, 19 Jul 2025 at 16:15, Taner Saydam ***@***.***> wrote:
> *TanerSaydam* created an issue (CarterCommunity/Carter#377)
> <https://github.com/CarterCommunity/Carter/issues/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
> <https://github.com/CarterCommunity/Carter/issues/377>, or unsubscribe
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> .
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> ID: ***@***.***>
>
There is a .NET 10 build with EF Core if you want to pull the code and run the sample - https://github.com/CarterCommunity/Carter/tree/net10/samples/EntityFwk