Humanizr/Humanizer · error · InvalidOperationException

Locale '{localeCode}.headings' defines unsupported property

Error message

Locale '{localeCode}.headings' defines unsupported property '{property}'. Supported properties: full, short.

What it means

The headings mapping accepts exactly two property names: 'full' and 'short'. Any additional key is unsupported because the heading set has a fixed schema, and the generator enumerates mapping keys to reject unknown properties early rather than silently ignoring them.

Source

Thrown at src/Humanizer.SourceGenerators/Common/LocaleYamlCatalog.cs:792

        }

        static HeadingSet? ResolveHeadings(
            string localeCode,
            ImmutableDictionary<string, SimpleYamlValue> features)
        {
            if (!features.TryGetValue("headings", out var headingValue))
            {
                return null;
            }

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

            foreach (var property in mapping.Values.Keys.Where(static property => property is not ("full" or "short")))
            {
                throw new InvalidOperationException(
                    $"Locale '{localeCode}.headings' defines unsupported property '{property}'. Supported properties: full, short.");
            }

            return new HeadingSet(
                ParseHeadingSequence(mapping, "full", localeCode),
                ParseHeadingSequence(mapping, "short", localeCode));
        }

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

View on GitHub (pinned to ffc2b77c0f)

Solutions

1. Remove or rename the unsupported property so only 'full' and 'short' remain.
2. If a narrower abbreviation is needed, place it under 'short:' and adjust the values.
3. Double-check spelling: it must be exactly 'full' and 'short'.

Example fix

# before
headings:
  full:
    - January
  medium:
    - Jan

# after
headings:
  full:
    - January
  short:
    - Jan

import yaml, pathlib
locales_dir = pathlib.Path('src/Humanizer/Locales')
allowed = {'full', 'short'}
for f in locales_dir.rglob('*.yml'):
    data = yaml.safe_load(f.read_text())
    if isinstance(data, dict) and isinstance(data.get('headings'), dict):
        extra = set(data['headings'].keys()) - allowed
        if extra:
            print(f'{f.name}: headings has unsupported keys: {extra}')

When it happens

Trigger: A locale's 'headings:' mapping contains a key other than 'full' or 'short', such as 'medium', 'narrow', or a typo like 'ful'.

Common situations: Copy-pasting CLDR-style property names (narrow, medium) that this schema does not support; typos in property names; leftover experimental keys.

Related errors

• Locale '{localeCode}.headings' must be a mapping.
• 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.

AI-assisted analysis of Humanizr/Humanizer@ffc2b77c0f (2026-08-13). Data as JSON: /api/errors/663d3dfd91f7f3e8. Report an issue: GitHub.