Humanizr/Humanizer · error · InvalidOperationException

Inflection lexemes must be mappings.

Error message

Inflection lexemes must be mappings.

What it means

Each item in the 'lexemes:' sequence must itself be a YAML mapping (an object with keys like id, pos, countability, forms, sources). ParseLexemes throws when a list item is a scalar, null, or nested sequence instead of a mapping.

Source

Thrown at src/Humanizer.SourceGenerators/Generators/ProfileCatalogs/InflectionCatalogParsing.cs:247

            {
                throw new InvalidOperationException("Active inflection bundle must define lexemes.");
            }

            if (lexemeSequence.Items.IsEmpty)
            {
                return allowEmpty
                    ? []
                    : throw new InvalidOperationException(
                        "Active inflection bundle must define lexemes.");
            }

            var ids = new HashSet<string>(StringComparer.Ordinal);
            var lexemes = ImmutableArray.CreateBuilder<InflectionLexemeInput>();
            foreach (var value in lexemeSequence.Items)
            {
                if (value is not SimpleYamlMapping lexeme)
                {
                    throw new InvalidOperationException("Inflection lexemes must be mappings.");
                }

                ValidateProperties(
                    lexeme,
                    "Inflection lexeme",
                    "id", "pos", "countability", "sense", "forms", "sources");
                var id = GetRequiredScalar(lexeme, "id", "Inflection lexeme must define id");
                if (!ids.Add(id))
                {
                    throw new InvalidOperationException($"Duplicate inflection lexeme id '{id}'.");
                }

                if (GetRequiredScalar(lexeme, "pos", $"Inflection lexeme '{id}' must define pos") != "noun")
                {
                    throw new InvalidOperationException($"Inflection lexeme '{id}' pos must be 'noun'.");
                }

                var countability = GetRequiredScalar(

View on GitHub (pinned to ffc2b77c0f)

Solutions

1. Make each list item a mapping containing id, pos, countability, forms, and sources

Example fix

# before
    lexemes:
      - 'zz.noun.cat'
      - 'zz.noun.dog'
# after
    lexemes:
      - id: 'zz.noun.cat'
        pos: 'noun'
        countability: 'count'
        forms: { ... }
        sources: [ 'fixture' ]

foreach (var item in lexemeSequence.Items)
    if (item is not SimpleYamlMapping)
        Report($"{locale}: each lexemes entry must be a mapping.");

static bool AllLexemesAreMappings(SimpleYamlSequence s) =>
    s.Items.All(i => i is SimpleYamlMapping);

When it happens

Trigger: An item under 'lexemes:' is a bare string/number or a nested sequence rather than a mapping.

Common situations: A YAML indentation slip flattening '- id: ...' into a flat list of scalars; pasting a list of ids instead of full lexeme objects.

Related errors

• Inflection defines unsupported quantity selector; expected '
• Inflection quantitySelector 'exact-numeric-singleton' requir
• Inflection quantitySelector 'exact-numeric-singleton' cannot
• Inflection display category 'one' is unreachable without qua
• Active inflection bundle must define lexemes.

AI-assisted analysis of Humanizr/Humanizer@ffc2b77c0f (2026-08-13). Data as JSON: /api/errors/bba0101084da0e4b. Report an issue: GitHub.