Humanizr/Humanizer · error · InvalidOperationException

Locale '{localeCode}.inflection' must be a mapping.

Error message

Locale '{localeCode}.inflection' must be a mapping.

What it means

The 'inflection' feature contains locale-specific inflection configuration as a keyed mapping. Because inflection rules are language-bound and must not cross language boundaries, the resolver also blocks cross-language inheritance; a non-mapping value is rejected outright.

Source

Thrown at src/Humanizer.SourceGenerators/Common/LocaleYamlCatalog.cs:828

        static SimpleYamlMapping? ResolveNumberFormatting(
            string localeCode,
            ImmutableDictionary<string, SimpleYamlValue> features)
        {
            return !features.TryGetValue("numberFormatting", out var formattingValue)
                ? null
                : formattingValue as SimpleYamlMapping
                ?? throw new InvalidOperationException($"Locale '{localeCode}.numberFormatting' must be a mapping.");
        }

        static SimpleYamlMapping? ResolveInflection(
            string localeCode,
            ImmutableDictionary<string, SimpleYamlValue> features)
        {
            return !features.TryGetValue("inflection", out var inflectionValue)
                ? null
                : inflectionValue as SimpleYamlMapping
                ?? throw new InvalidOperationException($"Locale '{localeCode}.inflection' must be a mapping.");
        }

        static ImmutableArray<string> ParseHeadingSequence(SimpleYamlMapping mapping, string key, string localeCode)
        {
            if (!mapping.TryGetValue(key, out var headingValue))
            {
                throw new InvalidOperationException($"Locale '{localeCode}.headings' must define '{key}'.");
            }

            if (headingValue is not SimpleYamlSequence sequence)
            {
                throw new InvalidOperationException($"Locale '{localeCode}.headings.{key}' must be a sequence.");
            }

            if (sequence.Items.Length != 16)
            {
                throw new InvalidOperationException($"Locale '{localeCode}.headings.{key}' must contain exactly 16 entries.");
            }

View on GitHub (pinned to ffc2b77c0f)

Solutions

1. Ensure the 'inflection:' value is a mapping with the expected inflection sub-keys.
2. Remove the key if the locale has no inflection data.
3. Verify that the locale does not inherit inflection from a different-language parent (the resolver nulls inherited inflection across language subtags).

Example fix

# before
inflection: german

# after
inflection:
  rules:
    plural: german

import yaml, pathlib
locales_dir = pathlib.Path('src/Humanizer/Locales')
for f in locales_dir.rglob('*.yml'):
    data = yaml.safe_load(f.read_text())
    if isinstance(data, dict) and 'inflection' in data:
        if not isinstance(data['inflection'], dict):
            print(f'{f.name}: inflection must be a mapping, got {type(data["inflection"]).__name__}')

When it happens

Trigger: A locale file sets 'inflection:' to a scalar or sequence rather than a mapping of inflection properties.

Common situations: Misstructuring inflection data; indentation errors; leaving a placeholder scalar after partial editing.

Related errors

• Phrase section '{path}' must be a mapping.
• Phrase section '{path}' defines unsupported property '{key}'
• Feature '{featureName}' in locale '{localeCode}' must be a s
• Locale '{localeCode}.grammar' must be a mapping.
• Locale '{localeCode}.phrases' must be a mapping.

AI-assisted analysis of Humanizr/Humanizer@ffc2b77c0f (2026-08-13). Data as JSON: /api/errors/ee50bd22190faec8. Report an issue: GitHub.