Fixing System.MissingMethodException In .NET 10

Nov 12, 2025 by Alex Johnson 48 views

.NET 10: Resolving System.MissingMethodException with EFCore.BulkExtensions

Encountering a System.MissingMethodException when working with EFCore.BulkExtensions in a .NET 10 environment can be a frustrating experience. This article dives deep into the common causes of this error, specifically focusing on the IReadOnlyNavigationBase.get_IsCollection() method, and provides practical solutions to get your bulk operations running smoothly. We'll explore the error context, analyze the code snippet provided, and offer a step-by-step guide to diagnose and resolve the problem.

Understanding the System.MissingMethodException

The System.MissingMethodException is a runtime exception that occurs when the Common Language Runtime (CLR) is unable to locate the definition of a method that your code is trying to call. In the context of EFCore.BulkExtensions, this often indicates an incompatibility between the version of the library you're using and the version of Entity Framework Core (EF Core) it's designed to work with. Let's break down why this happens and how to address it.

In this case, the error message Method not found: 'Boolean Microsoft.EntityFrameworkCore.Metadata.IReadOnlyNavigationBase.get_IsCollection()' points to a specific missing method within the EF Core metadata interfaces. This method, get_IsCollection(), is part of the IReadOnlyNavigationBase interface, which is used to represent navigation properties in your entity models. EFCore.BulkExtensions relies on this interface to understand the relationships between your entities and efficiently perform bulk operations.

When you encounter this exception, it typically means that the version of EF Core that EFCore.BulkExtensions is expecting is different from the version you have installed in your project. This mismatch can lead to the CLR being unable to find the get_IsCollection() method, resulting in the MissingMethodException.

To accurately resolve this, you should determine which version of Microsoft.EntityFrameworkCore is truly installed in your project. Sometimes implicit versioning can cause issues if you don't explicitly declare the version of the NuGet package in your project file (.csproj).

Analyzing the Code and Error Context

Let's examine the provided code snippet and the accompanying error information to gain a clearer understanding of the problem:

Code Snippet:

Subject.BulkInsert(
    elements,
    config =>
    {
        config.PreserveInsertOrder = true;
        config.SetOutputIdentity = true;
    });

Error Message:

System.MissingMethodException: Method not found: 'Boolean Microsoft.EntityFrameworkCore.Metadata.IReadOnlyNavigationBase.get_IsCollection()'.

   at EFCore.BulkExtensions.TableInfo.<>c__189`1.<LoadData>b__189_51(INavigation a)
   at EFCore.BulkExtensions.TableInfo.<>c__189`1.<LoadData>b__189_51(INavigation a)
   at System.Linq.Enumerable.IEnumerableWhereIterator`1.MoveNext()
   at EFCore.BulkExtensions.TableInfo.LoadData[T](DbContext context, Type type, IEnumerable`1 entities, Boolean loadOnlyPKColumn)
   at EFCore.BulkExtensions.TableInfo.CreateInstance[T](DbContext context, Type type, IEnumerable`1 entities, OperationType operationType, BulkConfig bulkConfig)
   at EFCore.BulkExtensions.DbContextBulkTransaction.ExecuteAsync[T](DbContext context, Type type, IEnumerable`1 entities, OperationType operationType, BulkConfig bulkConfig, Action`1 progress, CancellationToken cancellationToken)

The code snippet shows a basic usage of the BulkInsert method from EFCore.BulkExtensions. It's attempting to insert a collection of elements into the database, with configurations to preserve the insertion order and set the output identity. The error message indicates that the exception occurs during the LoadData phase within EFCore.BulkExtensions, specifically when it's trying to determine if a navigation property is a collection.

The stack trace provides valuable clues about the location of the error. It originates within the TableInfo.LoadData method, which is responsible for gathering metadata about the entity being processed. The error occurs when the library tries to access the IsCollection property of an INavigation object. This confirms that the issue is related to the version incompatibility of Microsoft.EntityFrameworkCore.

Furthermore, the message "But all codes are failing, BulkInsertOrUpdate etc..." suggests that this problem is not isolated to the BulkInsert method, but rather a more general issue affecting all bulk operations provided by the library. This reinforces the idea that the root cause is a fundamental incompatibility between EFCore.BulkExtensions and the installed EF Core version.

Step-by-Step Solution to Resolve the Exception

To resolve the System.MissingMethodException, follow these steps:

Identify Installed EF Core Version:

The first step is to determine the exact version of Microsoft.EntityFrameworkCore installed in your project. You can do this by checking the project's .csproj file or by examining the installed NuGet packages in your IDE (e.g., Visual Studio). Make sure to look at the explicit version number declared in your project.
Check EFCore.BulkExtensions Compatibility:

Next, determine the compatible EF Core version for your EFCore.BulkExtensions library. Refer to the library's documentation or NuGet package description to find the supported EF Core versions. This information is crucial for ensuring compatibility.
Update or Downgrade EF Core:

If the installed EF Core version is incompatible with EFCore.BulkExtensions, you'll need to either update or downgrade your EF Core package. Choose the EF Core version that is compatible with your EFCore.BulkExtensions library.
- To update EF Core: Use the NuGet Package Manager in Visual Studio or the .NET CLI to update the Microsoft.EntityFrameworkCore package to a compatible version. For example:
```
dotnet add package Microsoft.EntityFrameworkCore -v [Desired Version]
```
- To downgrade EF Core: Similarly, use NuGet Package Manager or the .NET CLI to downgrade the Microsoft.EntityFrameworkCore package to a compatible version. For example:
```
dotnet add package Microsoft.EntityFrameworkCore -v [Compatible Version]
```
Update EFCore.BulkExtensions (If Necessary):

In some cases, it might be beneficial to update EFCore.BulkExtensions to the latest version, as newer versions often include compatibility updates for newer EF Core releases. Use the NuGet Package Manager or the .NET CLI to update the EFCore.BulkExtensions package.
```
dotnet add package EFCore.BulkExtensions -v [Latest Version]
```
Clean and Rebuild the Project:

After updating or downgrading packages, clean and rebuild your project to ensure that all dependencies are correctly resolved and that there are no lingering references to older versions. This step is crucial for preventing unexpected behavior.
Verify the Fix:

Finally, run your code again to verify that the System.MissingMethodException is resolved. If the issue persists, double-check the installed package versions and ensure that they are compatible with each other.

Additional Troubleshooting Tips

Explicit Package Versions: Always explicitly specify package versions in your .csproj file to avoid implicit versioning issues. This ensures that you have control over the exact versions of the libraries used in your project.
Dependency Conflicts: Use the NuGet Package Manager's dependency resolution features to identify and resolve any dependency conflicts between different packages in your project.
Check Project References: Ensure that your project references the correct versions of the Microsoft.EntityFrameworkCore assemblies. Sometimes, incorrect references can cause version conflicts.
Examine Build Output: Carefully examine the build output for any warnings or errors related to assembly versions. These messages can provide valuable clues about potential versioning issues.

Example Scenario

Let's say you have Microsoft.EntityFrameworkCore version 5.0.0 installed, and EFCore.BulkExtensions requires version 3.1.0. You would need to downgrade your Microsoft.EntityFrameworkCore package to version 3.1.0 using the NuGet Package Manager or the .NET CLI:

dotnet add package Microsoft.EntityFrameworkCore -v 3.1.0

After downgrading, clean and rebuild your project, and then run your code again to verify that the exception is resolved.

Conclusion

The System.MissingMethodException when using EFCore.BulkExtensions often stems from version incompatibilities between EFCore.BulkExtensions and Microsoft.EntityFrameworkCore. By carefully identifying installed package versions, checking compatibility requirements, and updating or downgrading packages as needed, you can effectively resolve this issue and ensure that your bulk operations run smoothly. Remember to clean and rebuild your project after making changes to package versions, and always explicitly specify package versions in your .csproj file to avoid future conflicts.

For more information on Entity Framework Core and its related concepts, consider exploring the official Microsoft Documentation. This resource provides comprehensive guidance and best practices for working with EF Core in your .NET applications. It is important to always use the correct library for your specific implementation.