dotnet/reactive · error · ArgumentOutOfRangeException

bufferSize

Error message

bufferSize

What it means

Replay validates that bufferSize is non-negative; a negative replay buffer has no meaning. The message names parameter bufferSize; the guard `bufferSize < 0` throws ArgumentOutOfRangeException before the subject is created. Fix: use 0 or a positive buffer size.

Solutions

1. Pass a bufferSize of 0 (unbounded) or a positive element count.
2. Validate user-supplied buffer sizes before forwarding to Replay.

When it happens

Trigger: Thrown at AsyncRx.NET/System.Reactive.Async/Linq/Operators/Replay.cs:132 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of dotnet/reactive@94b5d5ab91 (2026-09-15). Data as JSON: /api/errors/64da66c501cee547. Report an issue: GitHub.

Appendix: source

Thrown at AsyncRx.NET/System.Reactive.Async/Linq/Operators/Replay.cs:132

        {
            if (source == null)
                throw new ArgumentNullException(nameof(source));
            if (selector == null)
                throw new ArgumentNullException(nameof(selector));
            if (scheduler == null)
                throw new ArgumentNullException(nameof(scheduler));

            return Multicast(source, () => new SequentialReplayAsyncSubject<TSource>(scheduler), selector);
        }

        public static IAsyncObservable<TResult> Replay<TSource, TResult>(this IAsyncObservable<TSource> source, Func<IAsyncObservable<TSource>, IAsyncObservable<TResult>> selector, int bufferSize)
        {
            if (source == null)
                throw new ArgumentNullException(nameof(source));
            if (selector == null)
                throw new ArgumentNullException(nameof(selector));
            if (bufferSize < 0)
                throw new ArgumentOutOfRangeException(nameof(bufferSize));

            return Multicast(source, () => new SequentialReplayAsyncSubject<TSource>(bufferSize), selector);
        }

        public static IAsyncObservable<TResult> Replay<TSource, TResult>(this IAsyncObservable<TSource> source, Func<IAsyncObservable<TSource>, IAsyncObservable<TResult>> selector, int bufferSize, IAsyncScheduler scheduler)
        {
            if (source == null)
                throw new ArgumentNullException(nameof(source));
            if (selector == null)
                throw new ArgumentNullException(nameof(selector));
            if (bufferSize < 0)
                throw new ArgumentOutOfRangeException(nameof(bufferSize));
            if (scheduler == null)
                throw new ArgumentNullException(nameof(scheduler));

            return Multicast(source, () => new SequentialReplayAsyncSubject<TSource>(bufferSize, scheduler), selector);
        }

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