C# Error CS0579 – Duplicate ‘{0}’ attribute

C# Error

CS0579 – Duplicate ‘{0}’ attribute

Reason for the Error & Solution

Duplicate ‘attribute’ attribute

It is not possible to specify the same attribute more than once unless the attribute specifies AllowMultiple=true in its .

Example

The following example generates CS0579.

// CS0579.cs  
using System;  
public class MyAttribute : Attribute  
{  
}  
  
[AttributeUsage(AttributeTargets.All,AllowMultiple=true)]  
public class MyAttribute2 : Attribute  
{  
}  
  
public class z  
{  
    [MyAttribute, MyAttribute]     // CS0579  
    public void zz()  
    {  
    }  
  
    [MyAttribute2, MyAttribute2]   // OK  
    public void zzz()  
    {  
    }  
  
    public static void Main()  
    {  
    }  
}