Humanizr/Humanizer · critical · InvalidOperationException

Locale '{localeCode}.surfaces.calendar.monthsGenitive' must

Error message

Locale '{localeCode}.surfaces.calendar.monthsGenitive' must be a sequence of exactly 12 strings.

What it means

Thrown by AddCalendarFeatures when surfaces.calendar.monthsGenitive is present and months is present, but the genitive list is not a YAML sequence of exactly 12 entries. Genitive months must mirror the nominative list one-to-one across all twelve months.

Source

Thrown at src/Humanizer.SourceGenerators/Common/CanonicalLocaleAuthoring.cs:483

                if (monthsSeq.Items.Any(static item => item is not SimpleYamlScalar))
                {
                    throw new InvalidOperationException(
                        $"Locale '{localeCode}.surfaces.calendar.months' items must be scalar strings.");
                }
            }

            if (calendarSurface.TryGetValue("monthsGenitive", out var monthsGenitiveValue))
            {
                if (!hasMonths)
                {
                    throw new InvalidOperationException(
                        $"Locale '{localeCode}.surfaces.calendar.monthsGenitive' requires 'months' to also be present.");
                }

                if (monthsGenitiveValue is not SimpleYamlSequence genitiveSeq || genitiveSeq.Items.Length != 12)
                {
                    throw new InvalidOperationException(
                        $"Locale '{localeCode}.surfaces.calendar.monthsGenitive' must be a sequence of exactly 12 strings.");
                }

                if (genitiveSeq.Items.Any(static item => item is not SimpleYamlScalar))
                {
                    throw new InvalidOperationException(
                        $"Locale '{localeCode}.surfaces.calendar.monthsGenitive' items must be scalar strings.");
                }
            }

            if (calendarSurface.TryGetValue("hijriMonths", out var hijriMonthsValue))
            {
                if (hijriMonthsValue is not SimpleYamlSequence hijriSeq || hijriSeq.Items.Length != 12)
                {
                    throw new InvalidOperationException(
                        $"Locale '{localeCode}.surfaces.calendar.hijriMonths' must be a sequence of exactly 12 strings.");
                }

View on GitHub (pinned to ffc2b77c0f)

Solutions

Provide exactly 12 genitive month strings in surfaces.calendar.monthsGenitive.
If a month has no distinct genitive form, repeat its nominative name for that slot rather than omitting it.
Rebuild to confirm the length guard passes.

Example fix

# before
calendar:
  months: [a, b, c, d, e, f, g, h, i, j, k, l]
  monthsGenitive: [genA, genB]
# after
calendar:
  months: [a, b, c, d, e, f, g, h, i, j, k, l]
  monthsGenitive: [genA, genB, genC, genD, genE, genF, genG, genH, genI, genJ, genK, genL]

Defensive patterns

Strategy: validation

Validate before calling

# Ensure surfaces.calendar.monthsGenitive is a 12-element sequence.
# Parse the YAML and assert: $gen -is [array] -and $gen.Count -eq 12.

Prevention

Provide exactly 12 genitive month strings to mirror 'months'.
Repeat the nominative name for months with no distinct genitive form rather than omitting.
Build after edits to catch length mismatches.

When it happens

Trigger: A locale YAML defines monthsGenitive with fewer/more than 12 entries, as a mapping, or as a scalar. The guard at CanonicalLocaleAuthoring.cs:481-485 requires a SimpleYamlSequence of length 12.

Common situations: Translating only some genitive forms and deferring the rest; a locale that has genitive forms for only some months (the schema still requires all 12); copy-paste miscount.

Related errors

AI-assisted analysis of Humanizr/Humanizer@ffc2b77c0f (2026-08-13). Data as JSON: /api/errors/d764ba22cd420ee0. Report an issue: GitHub.