How to resolve Entity Framework error: provider type "System.Data.Entity.SqlServer.SqlProviderServices" for the "System.Data.SqlClient" ADO.NET provider could not be loaded

This error occurs when the Entity Framework cannot find the System.Data.Entity.SqlServer.SqlProviderServices type for the System.Data.SqlClient ADO.NET provider. This can be caused by missing or incorrect references, or by not having the required configuration in your project.

Here are some steps you can take to resolve the error:

Ensure that you have the correct Entity Framework NuGet package installed. For Entity Framework 6, you should have the EntityFramework package, and for Entity Framework Core, you should have the Microsoft.EntityFrameworkCore.SqlServer package installed.
If you're using Entity Framework 6, make sure you have a reference to the EntityFramework.SqlServer.dll assembly in your project. You can do this by right-clicking the "References" folder in your project, selecting "Add Reference...", then browsing to the location of the EntityFramework.SqlServer.dll file and adding it to your project.
If you're using Entity Framework 6, ensure that your application's config file (usually App.config or Web.config) contains the following entry inside the <entityFramework> element:

<providers>
  <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
</providers>

Sometimes, the Entity Framework provider is not being used during runtime due to code optimization. To work around this issue, you can create an instance of the SqlProviderServices class in your application's entry point or in the constructor of your DbContext class. This will force the required assembly to be loaded:

using System.Data.Entity.SqlServer;

// ...

public class YourDbContext : DbContext
{
    // Add this static field to force the assembly to be loaded
    private static SqlProviderServices _ = SqlProviderServices.Instance;

    // ...
}

After making these changes, try rebuilding your project and running it again. The error should be resolved. If the issue persists, double-check your references, NuGet packages, and configuration settings to make sure they are correct.

Resolving 'Provider type could not be loaded' in Entity Framework: Addressing the "Provider type could not be loaded" error in Entity Framework.
```
// Ensure the correct provider is specified in the configuration
```
Fixing Entity Framework 'SqlProviderServices' not loaded error: Fixing the "SqlProviderServices not loaded" error in Entity Framework.
```
// Ensure the Entity Framework assembly is correctly referenced
```
Handling 'No Entity Framework provider found' exception: Handling the "No Entity Framework provider found" exception.
```
// Check the configuration for the correct provider
```
Troubleshooting ADO.NET provider loading issues in Entity Framework: Troubleshooting ADO.NET provider loading issues in Entity Framework.
```
// Check for missing or incorrect references to provider assemblies
```
Updating Entity Framework version to resolve provider type error: Updating the Entity Framework version to resolve provider type errors.
```
// Update the Entity Framework NuGet package to the latest version
```
Ensuring correct Entity Framework assembly references in C#: Ensuring correct assembly references for Entity Framework in C#.
```
// Check project references for Entity Framework assemblies
```
Checking Entity Framework configurations for provider issues: Checking Entity Framework configurations for provider-related issues.
```
// Verify the connection string and provider information in the configuration
```
Using Code First Migrations to resolve Entity Framework errors: Using Code First Migrations to resolve Entity Framework errors.
```
// Enable Code First Migrations and update the database
```
Updating packages.config for Entity Framework provider resolution: Updating the packages.config file to resolve Entity Framework provider issues.
```
// Ensure the correct version of Entity Framework is specified in packages.config
```