dotnet/reactive · error · ArgumentNullException

source7

Error message

source7

What it means

The 14-source Zip overload validates source7 at line 883; a null seventh sequence throws ArgumentNullException with parameter 'source7'. The public method checks inputs sequentially so the exception names exactly the offending parameter.

Solutions

1. Provide a valid observable for position 7; use Observable.Empty<TSource7>() when intentionally absent.
2. Fix the upstream producer that returned null for source7.
3. Add a guard loop or explicit checks over the source array before calling Zip.
4. Verify the 14-source call's argument order.

Example fix

// before
var zipped = Observable.Zip(s1, ..., s6, null, s8, ..., s14, selector);
// after
var zipped = Observable.Zip(s1, ..., s6, s7 ?? Observable.Empty<TSource7>(), s8, ..., s14, selector);

if (source7 == null) throw new ArgumentNullException(nameof(source7));

static IObservable<T> NonNull<T>(IObservable<T> s) => s ?? Observable.Empty<T>();

try { var zipped = Observable.Zip(source1, ..., source7, ...); } catch (ArgumentNullException ex) when (ex.ParamName == "source7") { /* substitute default source or abort */ }

When it happens

Trigger: Calling the 14-argument Observable.Zip with null as the seventh IObservable<TSource7> argument.

Common situations: A missing middle feed in a batch of streams (e.g. one sensor/service stream failed to initialize), or a null returned from a conditional stream-construction branch.

Related errors

• source3
• source5
• source9
• source15
• Value cannot be null. (Parameter 'observer')

AI-assisted analysis of dotnet/reactive@94b5d5ab91 (2026-09-15). Data as JSON: /api/errors/83754d58f911b360. Report an issue: GitHub.

Appendix: source

Thrown at Rx.NET/Source/src/System.Reactive/Linq/Observable.Multiple.Zip.cs:883

            if (source4 == null)
            {
                throw new ArgumentNullException(nameof(source4));
            }

            if (source5 == null)
            {
                throw new ArgumentNullException(nameof(source5));
            }

            if (source6 == null)
            {
                throw new ArgumentNullException(nameof(source6));
            }

            if (source7 == null)
            {
                throw new ArgumentNullException(nameof(source7));
            }

            if (source8 == null)
            {
                throw new ArgumentNullException(nameof(source8));
            }

            if (source9 == null)
            {
                throw new ArgumentNullException(nameof(source9));
            }

            if (source10 == null)
            {
                throw new ArgumentNullException(nameof(source10));
            }

            if (source11 == null)

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