How to Resolve Error "CS0768: Constructor cannot call itself through another constructor" in C#

The Compiler Error CS0768 is a logic error related to Constructor Chaining. The message reads: "Constructor cannot call itself through another constructor".

In C#, you can use the this(...) syntax to call one constructor from another within the same class. This is useful for reducing code duplication (e.g., a default constructor calling a parameterized constructor). However, if you create a cycle—where Constructor A calls Constructor B, and Constructor B calls Constructor A—you create an infinite recursion loop. The compiler detects this impossibility and blocks it with CS0768.

This guide explains how to structure your constructors to ensure a valid initialization path.

Understanding Constructor Chaining

Ideally, constructor chaining should be Linear:

1. public Class() calls this(int x)
2. public Class(int x) calls this(int x, string y)
3. public Class(int x, string y) does the actual work.

In a circular setup, the code never reaches the body of any constructor because it is endlessly hopping between the initialization headers (: this(...)).

Scenario: The Circular Dependency

This error occurs when two (or more) constructors delegate to each other, creating a closed loop.

Example of error

In this example, the parameterless constructor calls the parameterized one, but the parameterized one calls the parameterless one.

public class UserProfile
{
    public string UserName { get; set; }

    // Constructor A
    // ⛔️ Error CS0768: This calls Constructor B...
    public UserProfile() : this("DefaultUser")
    {
    }

    // Constructor B
    // ⛔️ Error CS0768: ...but Constructor B calls Constructor A.
    // Infinite loop detected.
    public UserProfile(string name) : this() 
    {
        UserName = name;
    }
}

Solution 1: Establish a "Master" Constructor

To fix this, you must pick one constructor to be the "Master" (or "Designated") constructor. This constructor should contain the actual initialization logic and should not call this(). All other constructors should funnel down to it.

public class UserProfile
{
    public string UserName { get; set; }

    // Constructor A (Convenience)
    // ✅ Correct: Calls Constructor B.
    public UserProfile() : this("DefaultUser")
    {
        // No logic needed here, it was delegated to B.
    }

    // Constructor B (Master)
    // ✅ Correct: Does NOT call 'this()'. It initializes the data.
    // This breaks the loop.
    public UserProfile(string name)
    {
        UserName = name;
    }
}

Solution 2: Use Optional Parameters

Often, circular dependencies happen because you are trying to provide default values. Instead of writing multiple constructors, you can often use a single constructor with Optional Parameters.

public class UserProfile
{
    public string UserName { get; set; }

    // ✅ Correct: One constructor handles both cases.
    // Calling new UserProfile() uses "DefaultUser".
    // Calling new UserProfile("Bob") uses "Bob".
    public UserProfile(string name = "DefaultUser")
    {
        UserName = name;
    }
}

note

This approach reduces code size and completely eliminates the possibility of circular chaining errors.

Conclusion

CS0768 prevents your program from crashing with a StackOverflowException during object creation.

1. Trace the Path: Follow the this(...) calls.
2. Find the Loop: Identify where the path circles back to the start.
3. Break the Chain: Ensure there is exactly one constructor at the bottom of the chain that does the actual work and does not delegate to this(...).