Humanizr/Humanizer · error · NotSupportedException

Grammatical case is not supported for time-unit symbols.

Error message

Grammatical case is not supported for time-unit symbols.

What it means

Thrown by DefaultHumanizeCore when both toSymbols is true and a grammaticalCase is specified. Time-unit symbols (e.g. "1h", "30m") are abbreviations that do not inflect by grammatical case, so requesting a case alongside symbols is logically contradictory.

Source

Thrown at src/Humanizer/TimeSpanHumanizeExtensions.cs:652

        TimeSpan timeSpan,
        int precision,
        bool countEmptyUnits,
        CultureInfo? culture,
        TimeUnit maxUnit,
        TimeUnit minUnit,
        string? collectionSeparator,
        bool toWords,
        bool toSymbols,
        GrammaticalCase? grammaticalCase)
    {
        if (grammaticalCase is { } requestedCase)
        {
            ValidateGrammaticalCase(requestedCase);
        }

        if (toSymbols && grammaticalCase is not null)
        {
            throw new NotSupportedException("Grammatical case is not supported for time-unit symbols.");
        }

        if (precision == 1 && !countEmptyUnits)
        {
            return HumanizeSinglePart(timeSpan, culture, maxUnit, minUnit, toWords, toSymbols, grammaticalCase);
        }

        var timeParts = CreatePrecisionLimitedTimeParts(
            timeSpan,
            culture,
            maxUnit,
            minUnit,
            precision,
            countEmptyUnits,
            toWords,
            toSymbols,
            grammaticalCase);

View on GitHub (pinned to ffc2b77c0f)

Solutions

1. Do not combine toSymbols=true with a grammaticalCase; choose words (toWords) for case support.
2. Set grammaticalCase to null when using symbols.
3. Split the call: use symbols without case, or words with case.

Example fix

// before
var s = ts.HumanizeWithCase(GrammaticalCase.Genitive, precision: 1, toSymbols: true);

// after
var s = ts.HumanizeWithCase(GrammaticalCase.Genitive, precision: 1);
// symbols are not requested; words support case inflection

static void AssertSymbolCaseCompat(bool toSymbols, GrammaticalCase? grammaticalCase)
{
    if (toSymbols && grammaticalCase is not null)
        throw new InvalidOperationException("Symbols and grammatical case are mutually exclusive.");
}

When it happens

Trigger: Calling a humanize overload that sets toSymbols=true while also passing a non-null grammaticalCase. This can happen indirectly through HumanizeWithCase when the code path routes to symbol output.

Common situations: Developer combines toSymbols and grammaticalCase in the same call expecting case-aware abbreviations. Misunderstanding that symbols are case-invariant. Passing both parameters from a configuration object.

Related errors

• The configured ITimeSpanHumanizeStrategy does not support gr
• The formatter for '{culture?.Name ?? CultureInfo.CurrentCult
• Custom strategy type '{GetType().FullName}' must explicitly
• Custom formatter type '{GetType().FullName}' must explicitly
• Culture '{Culture.Name}' has no grammatical-case classificat

AI-assisted analysis of Humanizr/Humanizer@ffc2b77c0f (2026-08-13). Data as JSON: /api/errors/79bd7a05de065eba. Report an issue: GitHub.