Transitive Dependency – Challenges and Approaches in .NET

Imagine you are developing a .NET application that runs perfectly at first. Suddenly, however, unexpected runtime errors occur—even though your main project does not explicitly include any additional packages. How can this phenomenon be explained? Often, the cause is a transitive dependency: a library such as Entity Framework Core is silently included in your project via another NuGet package. In complex application scenarios, this issue can lead to version conflicts or even hard-to-diagnose runtime errors like the MissingMethodException. Without targeted management of these dependencies, the effort required for error resolution can become significant.

---

1. Basics and Problem Statement

1.1 Transitive References vs. Transitive Dependencies

• Transitive References:
  
  In a multi-layered solution structure, for example, Project A directly references Project B, which in turn uses Project C. In this way, Project A has an indirect (transitive) reference to Project C—even if it is not explicitly listed in the .csproj file.

• Transitive Dependencies:
  
  With external NuGet packages, the problem appears when they are brought in by a referenced package and do not show up in the main project’s .csproj file. For instance, if Project A uses a package (e.g., PackageX) that internally references EF Core in a specific version, then EF Core is included transitively—even though Project A never explicitly added it.

Isn’t it remarkable how quickly such subtle dependency chains can emerge in large projects without being noticed?

1.2 A Typical Scenario in .NET

In many .NET applications, Entity Framework Core (EF Core) is used as the data access library. Even if the main project does not directly reference EF Core, it can be silently included as a transitive dependency via another utility or data access package. Initially, everything seems to work smoothly—EF Core provides a stable API. However, when updating the .NET framework or integrating new features, version conflicts may occur that eventually lead to hard-to-diagnose runtime errors.

---

2. Detailed Solution Approaches

To prevent the unwanted propagation of packages, two main approaches are available: the targeted restriction of individual packages using PrivateAssets="all" or the complete deactivation of transitive project references with <DisableTransitiveProjectReferences>true</DisableTransitiveProjectReferences>. Both approaches are critically examined below.

2.1 PrivateAssets="all"

By adding the attribute PrivateAssets="all" in the PackageReference, you prevent the respective library from being passed on to other projects in the dependency hierarchy. This way, the package—and its transitive dependencies—remain available only within the current project.

Advantages:

• Granularity: You decide on a package-by-package basis whether a dependency should be inherited.
• Avoidance of Side Effects: Problematic libraries are not automatically transferred to subordinate projects.

Disadvantages:

• Increased Configuration Effort: If another project needs the same library, it must be explicitly referenced again.

Example:

<ItemGroup>
  <PackageReference Include="SomeDataAccessPackage" Version="1.2.3" PrivateAssets="all" />
</ItemGroup>

Could it be that in complex environments the administrative effort for such package-specific configuration outweighs the benefits?

2.2 DisableTransitiveProjectReferences

With the global setting true in the .csproj file, you prevent the automatic propagation of all transitive project references. Every project must then explicitly list all the required packages.

Advantages:
• Increased Transparency: All dependencies are explicitly visible and controllable.
• Prevention of Unintended Inclusions: No “hidden” libraries are automatically added to the project.

Disadvantages:
• Higher Maintenance Effort: Explicitly listing all dependencies can create a significant administrative overhead, especially in larger projects.
• Risk of Omissions: Essential dependencies might accidentally be overlooked, leading to compile-time or runtime errors.

Example:

<PropertyGroup>
  <DisableTransitiveProjectReferences>true</DisableTransitiveProjectReferences>
</PropertyGroup>

Given the additional effort, is it really practical to explicitly declare all dependencies?

2.3 Comparison of Both Approaches

Criterion	PrivateAssets="all"	DisableTransitiveProjectReferences
Granularity	Package-specific control	Global deactivation – all dependencies must be explicitly referenced
Maintenance Effort	Requires individual adjustments per project	Higher maintenance effort due to separate management of all references
Clarity	Can lead to opaque dependency chains in complex structures	Clear separation, but increases the risk of overlooking essential packages
Flexibility	High flexibility in isolated control of individual packages	Strict control, but less adaptability

3. Practical Example: Abstraction and Interface Encapsulation

Consider a specific application: a .NET Standard library named Common encapsulates various helper methods and tools and internally includes a data access package that brings EF Core as a transitive dependency. In this case, it is advisable not to expose EF Core-specific classes in the public API; instead, these should be abstracted through interfaces.

Example Implementation:

// In Common
public interface IDataService
{
    IEnumerable<string> GetData();
}

internal class EfDataService : IDataService
{
    public IEnumerable<string> GetData()
    {
        // Internal use of EF Core
        return new List<string> { "Data from EF Core" };
    }
}

public static class DataServiceFactory
{
    public static IDataService CreateService()
    {
        return new EfDataService();
    }
}

Configuration in Common.csproj:

<ItemGroup>
  <PackageReference Include="SomeDataAccessPackage" Version="1.2.3" PrivateAssets="all" />
</ItemGroup>

This approach ensures that EF Core remains exclusively available internally—the main application only interacts with the interface without needing to know the underlying implementation.

4. Advanced Strategies and Alternative Approaches

In addition to the configuration options discussed above, other strategies can help minimize version conflicts and the issues of transitive dependencies:
• Binding Redirects:
Especially in older .NET Framework applications, binding redirects can help resolve conflicts between different versions of the same library.
• Modular Architectures:
Separating the application into clearly defined modules allows for targeted isolation of dependencies. This makes it easier to control unwanted side effects.

Should we not always question whether a focus solely on .csproj configurations in highly complex systems is truly the optimal solution?

5. Summary and Outlook

Transitive dependencies represent a serious issue in complex .NET projects. Seemingly insignificant libraries like EF Core can—when included via other NuGet packages—lead to significant version conflicts and runtime errors. Consistent separation of dependencies and the targeted use of measures such as PrivateAssets="all" or offer practical solutions. It is essential to weigh whether the administrative effort is justified by the benefits and how long-term maintainability can be ensured.

By using abstractions, explicit references, and additional measures such as binding redirects, developers can not only create a more stable codebase but also reduce ongoing maintenance efforts. Regularly reviewing dependency hierarchies using tools like dotnet list package --include-transitive or NDepend is indispensable.

Is it not ultimately the task of every developer to continually question whether the current architecture still meets the growing demands of modern applications?

I think so….!