DLL Dancing: The .NET Developer’s worst nightmare and how to fix it

You’re working on a .NET project, and feeling pretty good about your progress. Your code is in shape, the features are coming together, and you decide it’s time to add a new DLL. Easy, right? Just copy and paste the DLL into the dependency folder, and you’re all set. But as soon as you hit “Build,” an error message pops up, announcing a new dependency is missing. You add that DLL, only to be greeted by another error. Before you know it, you’re caught in the whirlwind of what my wise old colleague would dramatically call the “DLL Dance.”

Photo by Zac Ong on Unsplash

This isn’t just a quirky term — it’s a dance as old as .NET itself, where the steps are dictated by DLLs and the rhythm is set by dependency chains. While it may sound similar to the notorious “DLL Hell” (where you were plagued by version conflicts and dependency issues), the DLL Dance is a bit different. Unlike DLL Hell, which was often about massive conflicts between different versions of the same DLL, the DLL Dance usually involves a more meticulous and repetitive process of adding and removing DLLs to get everything aligned just right.

The DLL Dance: A Step-by-Step Guide

Imagine you’re adding a new feature to your application. You spot a DLL that seems to be the perfect fit. You add it to your project, only to face this error message:

System.IO.FileNotFoundException: Could not load file or assembly 'SomeDependency.dll'

You check the DLL’s requirements and find that you’re missing another dependency. You add that one, and soon you’re hit with another error. It feels like an endless loop where each fix creates a new problem.

Why Does the DLL Dance Happen?

Here’s a behind-the-scenes look at why this dance happens:

1. Dependency Chains: DLLs can depend on other DLLs. Adding a new DLL might require additional dependencies that you didn’t anticipate. For example, if FeatureLibrary.dll relies on UtilityLibrary.dll, you need to ensure both are included in your project.
2. Version Mismatches: Different DLLs may require different versions of the same library. For instance, if PluginA.dll needs version 1.2.0 of CoreLibrary.dll and PluginB.dll needs version 1.3.0, conflicts can arise if they’re not handled properly.
3. NuGet Package Management: NuGet helps, but sometimes packages can have conflicting dependencies or require specific versions. Your packages.config might look like this:

<package id="Newtonsoft.Json" version="13.0.1" targetFramework="net5.0" />

But if another DLL needs a different version, you’ll have to manage these conflicts.

4. Assembly Binding Redirects: If you have multiple DLLs requiring different versions of the same assembly, you may need to configure binding redirects in your app.config or web.config:

<configuration>   
  <runtime>     
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">       
      <dependentAssembly>         
        <assemblyIdentity name="SomeAssembly" publicKeyToken="1234567890abcdef" culture="neutral" />         
        <bindingRedirect oldVersion="0.0.0.0-1.0.0.0" newVersion="1.0.0.0" />       
      </dependentAssembly>     
    </assemblyBinding>   
  </runtime> 
</configuration>

How to Avoid the DLL Dance

Here are some tips to help you avoid getting caught in the DLL Dance:

1. Use NuGet Packages: Manage your dependencies through NuGet to avoid manually handling DLLs. NuGet takes care of versioning and dependencies for you.
2. Check Dependencies: Before adding a new DLL, review its dependencies. Use tools like dotnet peek to ensure you have all the required components.
3. Update Regularly: Keep your libraries and NuGet packages up-to-date to minimize conflicts and dependency issues.
4. Build Configuration: Ensure your build configurations (Debug vs. Release) are consistent to avoid version mismatch issues.
5. Use Assembly Binding Redirects: Properly configure assembly binding redirects to handle version conflicts between different DLLs.
6. Clean and Rebuild: Sometimes, simply cleaning your solution and performing a rebuild can resolve dependency issues.

The Takeaway

The DLL Dance can be a frustrating experience, but with a bit of preparation and the right tools, you can avoid getting caught in a never-ending loop of dependency issues. So, the next time you find yourself in a DLL dance-off, remember these tips and steps to stay in control of the situation.

And that’s a wrap! If you’ve read this far, it means you liked this article. If that’s true, please leave a clap. I publish similar articles every week, so feel free to follow me for more.