What causes "'{path}.provenance' must not be empty." in Humanizr/Humanizer?

Populate the provenance sequence with at least one valid source ID defined in the locale's sources registry.

Humanizr/Humanizer · error · InvalidOperationException

'{path}.provenance' must not be empty.

Error message

'{path}.provenance' must not be empty.

What it means

Thrown by ParseProvenance when required is true, the provenance key exists and is a valid sequence, but the sequence contains zero items. After iterating, the parser checks result.Count == 0 and throws if the list is empty.

Source

Thrown at src/Humanizer.SourceGenerators/Common/DurationCaseModels.cs:1073

            {
                if (item is not SimpleYamlScalar scalar || string.IsNullOrWhiteSpace(scalar.Value))
                {
                    throw new InvalidOperationException(
                        $"'{path}.provenance' must contain non-empty source identifiers.");
                }

                if (!seen.Add(scalar.Value))
                {
                    throw new InvalidOperationException(
                        $"'{path}.provenance' contains duplicate source '{scalar.Value}'.");
                }

                result.Add(scalar.Value);
            }

            if (required && result.Count == 0)
            {
                throw new InvalidOperationException($"'{path}.provenance' must not be empty.");
            }

            return result.MoveToImmutable();
        }

        static void ValidateProvenance(
            ImmutableArray<string> provenance,
            ImmutableDictionary<string, DurationCaseSource> sources,
            string path)
        {
            foreach (var sourceId in provenance.Where(sourceId => !sources.ContainsKey(sourceId)))
            {
                throw new InvalidOperationException(
                    $"'{path}.provenance' references unknown source '{sourceId}'.");
            }
        }

        static string RequireScalar(SimpleYamlMapping mapping, string key, string path) =>

View on GitHub (pinned to ffc2b77c0f)

Solutions

Populate the provenance sequence with at least one valid source ID defined in the locale's sources registry.
Rebuild to confirm the non-empty provenance is accepted.

Example fix

# before
provenance: []
# after
provenance: [cldr-42]

Defensive patterns

Strategy: validation

Validate before calling

# Verify required provenance is non-empty
# python: if required: assert len(unit['provenance']) > 0, 'provenance must not be empty'

Prevention

Never leave provenance as an empty list placeholder; populate it with at least one source ID.
If unsure of the source, add a placeholder source entry and reference it, then update later.
Build immediately after adding the provenance key to catch empty-list errors.

When it happens

Trigger: The 'provenance' key is present and is a valid YAML sequence, but the sequence is empty (e.g. provenance: []).

Common situations: A contributor adds the provenance key as an empty list as a placeholder, or a YAML template generates an empty sequence. The generator requires at least one source for phrase, sameRenderedAs, and notApplicable realizations.

Related errors

AI-assisted analysis of Humanizr/Humanizer@ffc2b77c0f (2026-08-13). Data as JSON: /api/errors/e71d799a12729755. Report an issue: GitHub.