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How to Resolve Error "CS0205: Cannot call an abstract base member: 'method'" in C#

The Compiler Error CS0205 is a logic error related to Inheritance. The message reads: "Cannot call an abstract base member: 'BaseClass.MethodName'".

In C#, an abstract method is a contract. It defines a signature (name, return type, parameters) but provides no implementation (no code body). Because the base method essentially "does not exist" in executable form, trying to call it using the base keyword is impossible. The runtime would have no instructions to execute.

This error most commonly occurs due to "muscle memory," where developers automatically add base.Method() when overriding a method, forgetting that the method being overridden is abstract.

Understanding Abstract vs. Virtual​

To fix this, you must distinguish between two keywords:

  • virtual: The base class provides a default implementation (code). You can call base.Method() to run that default code.
  • abstract: The base class provides no implementation. It is purely a placeholder requiring derived classes to supply the logic. You cannot call base.Method() because there is nothing to call.

Scenario 1: The "Habitual" Base Call​

When overriding standard virtual methods (like ToString or OnLoad), it is common practice to call base.Method() to ensure the parent class executes its logic. Developers often apply this pattern to abstract methods by mistake.

Example of error:

public abstract class Animal
{
    // Abstract: No body, just a definition.
    public abstract void MakeSound();
}

public class Dog : Animal
{
    public override void MakeSound()
    {
        // ⛔️ Error CS0205: Cannot call an abstract base member: 'Animal.MakeSound'
        // The compiler looks at Animal.MakeSound and sees no code block { ... }.
        // Therefore, it forbids this call.
        base.MakeSound(); 
        
        System.Console.WriteLine("Bark");
    }
}

Solution 1: Remove the Base Call (Standard Fix)​

Since the abstract method contains no logic, calling it serves no purpose. Simply delete the line calling base.

public class Dog : Animal
{
    public override void MakeSound()
    {
        // ✅ Correct: We provide the full implementation here.
        // No need (and no way) to ask the parent to do anything.
        System.Console.WriteLine("Bark");
    }
}
note

This is the correct solution in 99% of cases. The child class is responsible for the entirety of the behavior for abstract methods.

Solution 2: Change Abstract to Virtual (Design Change)​

If you actually intended for the base class to have some common logic that all children should run, then declaring the method as abstract was a mistake in your design. You should change it to virtual and provide a method body.

Solution: modify the base class to include the common code.

public abstract class Animal
{
    // ✅ Correct: Changed 'abstract' to 'virtual' and added a body.
    public virtual void MakeSound()
    {
        System.Console.WriteLine("Animal is preparing to make a sound...");
    }
}

public class Dog : Animal
{
    public override void MakeSound()
    {
        // ✅ Correct: Now valid, because 'base.MakeSound' actually has code to run.
        base.MakeSound(); 
        
        System.Console.WriteLine("Bark");
    }
}

Output:

Animal is preparing to make a sound...
Bark

Conclusion​

CS0205 is the compiler preventing you from calling a phantom method.

  1. Check the Base: Is the method marked abstract?
  2. Option A (Fix): If it is abstract, delete the base.Method() call in your override.
  3. Option B (Refactor): If you need to call the base, change the base method from abstract to virtual and write the logic there.

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