Code inspection: '??' condition is never null according to nullable reference types' annotations

This inspection reports a ?? or ??= expression when nullable annotations or API contracts already say the left side should never be null. In that case, the fallback value is unreachable and usually indicates redundant code or a mismatched nullability annotation.

Example

                #nullable enable
                using System.Diagnostics.CodeAnalysis;
                class C
                {
                    [DisallowNull]
                    private string? _name = "";
                    string GetName()
                    {
                        return _name ?? "Unknown";
                    }
                }
            

                #nullable enable
                using System.Diagnostics.CodeAnalysis;
                class C
                {
                    [DisallowNull]
                    private string? _name = "";
                    string GetName()
                    {
                        return _name;
                    }
                }
            

Quick-fix

Depending on the situation, the quick-fix can also make the member or parameter nullable instead of removing the unreachable fallback.

13 April 2026