Dictionary TryGetValue(TKey, TValue) - Unhandled exception.

[Was85]

I found it weird to get an Unhandled exception. System.ArgumentNullException: Value cannot be null. (Parameter 'key') when I pass null into a function called TryGetValue(TKey, TValue).

I know it's stated clearly in the Docs that this will happen when pass null. However, I believe this should be changed and returned as false instead of throwing an exception.

[koszeggy]

I believe this should be changed

Modifying this behavior would be a breaking change. And considering that keys cannot be null this behavior makes sense.

But you can always define a new extension method, eg.

public static bool MyTryGetValue<TKey, TValue>(this IDictionary<TKey, TValue> dict,
    TKey key, [MaybeNullWhen(false)]out TValue value)
{
    if (key == null)
    {
        value = default;
        return false;
    }

    return dict.TryGetValue(key, out value);
}

And just a side note: I needed to create an AllowNullDictionary type once. But please note that its TryGetValue explicitly contains a [CanBeNull] attribute for the key parameter, which triggered CS8767 (Nullability of reference types in type of parameter doesn't match implicitly implemented member) that I needed to suppress, which indicates that the current behavior is very much expected.

[HaloFour]

Also, this would be a request to the runtime repository, which handles the base class libraries and APIs for .NET.