7 Hilarious Constructor Fails in .NET That Will Make You Facepalm 🤦‍♂️

I’ve been coding in .NET for years, and one thing I’ve learned is this: constructors are supposed to set up your classes… but in practice, they often set you up for disaster. From dependency injection overloads to circular references that crash your app, .NET constructors can create some of the funniest (and most painful) fails.

Here are 7 constructor fails in .NET that will make you laugh, cry, and maybe even fix your own code 👇

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1. The Infinite Parameter Constructor 📜

public class OrderService
{
    public OrderService(
        IUserRepository userRepository,
        IProductRepository productRepository,
        IOrderValidator orderValidator,
        IEmailService emailService,
        ILogger logger,
        IDiscountCalculator discountCalculator,
        IPaymentGateway paymentGateway)
    {
        // constructor longer than the entire class
    }
}

🔴 Fail: Your constructor looks like a shopping list.
✅ Fix: Use the Facade pattern, or refactor responsibilities into smaller services.

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2. Forgetting the Default Constructor 🤷

public class ReportGenerator
{
    public ReportGenerator(string path) { }
}

And then somewhere:

var report = new ReportGenerator(); // boom! Compiler error

🔴 Fail: You forgot the parameterless constructor.
✅ Fix: Always add a default constructor if your class might be instantiated without arguments.

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3. The Circular Dependency 💫

public class ServiceA
{
    public ServiceA(ServiceB b) { }
}

public class ServiceB
{
    public ServiceB(ServiceA a) { }
}

🔴 Fail: App runs → DI container explodes with System.InvalidOperationException: A circular dependency was detected.
✅ Fix: Break the cycle with an interface, or rethink your architecture.

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4. Logic in Constructors 🔥

public class FileReader
{
    public FileReader(string path)
    {
        var data = File.ReadAllText(path); // oops, exception here!
    }
}

🔴 Fail: You put heavy logic (like I/O) in the constructor.
✅ Fix: Keep constructors lightweight. Use methods or InitializeAsync() for heavy work.

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5. Multiple Constructors, Zero Clarity 😵

public class UserManager
{
    public UserManager() { }
    public UserManager(string name) { }
    public UserManager(int id) { }
}

🔴 Fail: Nobody knows which constructor should be used.
✅ Fix: Use factory methods (CreateWithName(), CreateWithId()) for clarity.

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6. Dependency Injection Gone Wrong 💉

public class PaymentProcessor
{
    public PaymentProcessor(IServiceProvider provider)
    {
        var repo = provider.GetService<IRepository>(); // service locator anti-pattern
    }
}

🔴 Fail: You inject IServiceProvider and resolve everything manually.
✅ Fix: Inject dependencies directly instead of abusing the service provider.

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7. Constructor Throwing Exceptions 🚨

public class ConfigLoader
{
    public ConfigLoader()
    {
        throw new Exception("No config file found!");
    }
}

🔴 Fail: Exceptions in constructors make your app fail at startup.
✅ Fix: Constructors should only set up state. Handle runtime errors in methods.

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Conclusion 🎯

Constructors in .NET can make or break your app. If you’ve ever written a monster constructor or caused a circular dependency, you know the pain. By keeping constructors clean, lightweight, and focused, you’ll save yourself (and your teammates) countless headaches.

💬 Which constructor fail have you committed? Share your stories — let’s laugh (and learn) together!