C# Error CS4032 – The ‘await’ operator can only be used within an async method. Consider marking this method with the ‘async’ modifier and changing its return type to ‘Task<{0}>‘.

C# Error

CS4032 – The ‘await’ operator can only be used within an async method. Consider marking this method with the ‘async’ modifier and changing its return type to ‘Task<{0}>‘.

Reason for the Error & Solution

The ‘await’ operator can only be used within an async method. Consider marking this method with the ‘async’ modifier and changing its return type to ‘Task<T>’.

Example

The following sample generates CS4032:

// CS4032.cs (7,9)
using System.Collections.Generic;
using System.Threading.Tasks;

class C
{
    static IAsyncEnumerator<int> M(int value)
    {
        yield return value;
        await Task.CompletedTask;
    }
}

To correct this error

To correct this error, change the signature of method M to make it asynchronous:

using System.Collections.Generic;
using System.Threading.Tasks;

class C
{
    static async IAsyncEnumerator<int> M(int value)
    {
        yield return value;
        await Task.CompletedTask;
    }
}