Code inspection: The 'EnumeratorCancellation' attribute is only effective on a parameter of type 'CancellationToken' in an async-iterator method returning 'IAsyncEnumerable<>'.

This inspection reports [EnumeratorCancellation] used where it has no effect. The attribute is only meaningful on a CancellationToken parameter of an async iterator method that returns IAsyncEnumerable<T>. On other parameter types or other method shapes, it does nothing.

Example

                using System.Collections.Generic;
                using System.Runtime.CompilerServices;
                class C
                {
                    public async IAsyncEnumerable<int> M([EnumeratorCancellation] int token)
                    {
                        yield return token;
                    }
                }
            

                using System.Collections.Generic;
                class C
                {
                    public async IAsyncEnumerable<int> M(int token)
                    {
                        yield return token;
                    }
                }
            

Quick-fix

The quick-fix removes the ineffective attribute. Another valid manual fix is to change the method so the attribute is applied to a CancellationToken parameter of an async iterator returning IAsyncEnumerable<T>.

21 April 2026