SqlParameterCollection only accepts non-null SqlParameter type objects, not SqlParameter objects

When you try to execute a query with EF Core that has parameters, you get the following exception:

System.InvalidCastException: The SqlParameterCollection only accepts non-null SqlParameter type objects, not SqlParameter objects

The error message is confusing because it’s not showing the full type names. This error means you’re using System.Data.SqlClient.SqlParameter, but EF Core only accepts Microsoft.Data.SqlClient.SqlParameter. Note: They made the error message smarter in EF Core 7 by showing full type names.

Solution – Use Microsoft.Data.SqlClient.SqlParameter

You need to use Microsoft.Data.SqlClient.SqlParameter instead of System.Data.SqlClient.SqlParameter with EF Core. Here’s an example of executing a parameterized query with Microsoft.Data.SqlClient.SqlParameter:

var nameParameter = new Microsoft.Data.SqlClient.SqlParameter("@Name", "Bob");
dbContext.Database.ExecuteSqlInterpolated($"INSERT INTO dbo.Names (Name) VALUES ({nameParameter})");
Code language: C# (cs)

This SqlParameter type is part of the Microsoft.Data.SqlClient package. Since you’re using EF Core with SQL Server, you should already have this package (it’s part of Microsoft.EntityFrameworkCore.SqlServer). If you don’t have the package, you can install it:

Install-Package Microsoft.Data.SqlClient
Code language: PowerShell (powershell)

Note: This is using the Package Manager Console in Visual Studio (View > Other Windows > Package Manager Console).