elsa-workflows/elsa-core · error · InvalidOperationException

Duplicate ingress source registration for name

Error message

Duplicate ingress source registration for name '{source.Name}'.

What it means

IngressSourceRegistry.EnsureMaterialized lazily builds entries from the configured sources factory and requires each source to have a unique name. When two or more registered ingress sources share the same name, TryAdd fails and InvalidOperationException is thrown. This is a configuration invariant protecting name-based lookup of ingress sources.

Solutions

1. Find the duplicate registration and give each ingress source a distinct Name.
2. Guard registration code so the same source is not added twice (e.g. check if already registered before adding).
3. Review DI setup for duplicate AddIngressSource-style calls across feature modules.
4. Add a startup-time uniqueness check for source names to fail fast with a clearer message.

Example fix

// before
options.AddSource(new ConsoleIngressSource { Name = "console" });
options.AddSource(new FileIngressSource { Name = "console" }); // duplicate

// after
options.AddSource(new ConsoleIngressSource { Name = "console" });
options.AddSource(new FileIngressSource { Name = "console-file" });

var names = options.Sources.Select(s => s.Name).ToList();
var duplicates = names.GroupBy(n => n).Where(g => g.Count() > 1).ToList();
if (duplicates.Any()) throw new InvalidOperationException($"Duplicate ingress source names: {string.Join(", ", duplicates.Select(d => d.Key))}");

try
{
    _ = registry.Sources;
}
catch (InvalidOperationException ex) when (ex.Message.StartsWith("Duplicate ingress source registration"))
{
    logger.LogCritical(ex, "Ingress source names must be unique.");
}

When it happens

Trigger: Registering two or more ingress sources with the same Name via the diagnostics console-logs ingress source registration, then first accessing Sources, Snapshot, MarkPauseFailedAsync, RecordTransition, or GetState, which triggers materialization.

Common situations: Two features both registering a source with a default name (e.g. 'console'); copying registration code without renaming the source; duplicate AddX calls in DI configuration.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

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AI-assisted analysis of elsa-workflows/elsa-core@fe9217bdfa (2026-09-13). Data as JSON: /api/errors/609ecaca094fa13f. Report an issue: GitHub.

Appendix: source

Thrown at src/modules/Elsa.Workflows.Runtime/Services/IngressSourceRegistry.cs:55

            return _entries.Values.Select(e => e.Source).ToArray();
        }
    }

    private void EnsureMaterialized()
    {
        // Double-checked lock: a `_entries.Count > 0` guard is not atomic with the population loop, so concurrent
        // first callers could both observe an empty dictionary, both iterate _sourcesFactory.Value, and both call
        // TryAdd — losing the duplicate-name guarantee and crashing the second caller's execution cycle start with
        // "Duplicate ingress source registration". A short lock around the one-time population is sufficient;
        // steady-state reads short-circuit on the volatile flag without taking the lock.
        if (_materialized) return;
        lock (_materializeSync)
        {
            if (_materialized) return;
            foreach (var source in _sourcesFactory.Value)
            {
                if (!_entries.TryAdd(source.Name, new Entry(source)))
                    throw new InvalidOperationException($"Duplicate ingress source registration for name '{source.Name}'.");
            }
            _materialized = true;
        }
    }

    /// <inheritdoc />
    public IReadOnlyCollection<IngressSourceSnapshot> Snapshot()
    {
        EnsureMaterialized();
        return _entries.Values
            .Select(e => new IngressSourceSnapshot(e.Source.Name, e.State, e.LastError, e.LastTransitionAt))
            .ToArray();
    }

    /// <inheritdoc />
    public ValueTask MarkPauseFailedAsync(string name, string reason, Exception? error = null)
    {
        EnsureMaterialized();

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