OrchardCMS/OrchardCore · error · NotSupportedException

The calendar is not supported.

Error message

The calendar is not supported.

What it means

BclCalendars.GetCalendarByName maps a CalendarName enum value to an Noda Time CalendarSystem. Only Gregorian, Julian, Persian, and UmAlQura are mapped; any other value (or an out-of-range cast) hits the default arm, which throws NotSupportedException.

Solutions

1. Use a supported calendar: Gregorian, Julian, Persian, or UmAlQura.
2. Validate/normalize the calendar setting before calling (Enum.IsDefined plus an allow-list check).
3. If a new CalendarName member was introduced, extend the switch expression to map it to a CalendarSystem.
4. Catch NotSupportedException at the boundary and fall back to the ISO/Gregorian calendar.

Example fix

// before
var calendar = BclCalendars.GetCalendarByName((CalendarName)7); // throws

// after
var name = Enum.IsDefined(typeof(CalendarName), 7) && name is CalendarName.Gregorian or CalendarName.Julian or CalendarName.Persian or CalendarName.UmAlQura
    ? (CalendarName)7 : CalendarName.Gregorian;
var calendar = BclCalendars.GetCalendarByName(name);

static readonly CalendarName[] Supported = [CalendarName.Gregorian, CalendarName.Julian, CalendarName.Persian, CalendarName.UmAlQura];
bool isSupported = Enum.IsDefined(typeof(CalendarName), value) && Supported.Contains(value);

bool IsSupportedCalendar(CalendarName name) =>
    name is CalendarName.Gregorian or CalendarName.Julian or CalendarName.Persian or CalendarName.UmAlQura;

try { calendar = BclCalendars.GetCalendarByName(name); }
catch (NotSupportedException) { calendar = CalendarSystem.Iso; /* fallback to Gregorian */ }

When it happens

Trigger: Calling GetCalendarByName with a CalendarName value other than Gregorian, Julian, Persian, or UmAlQura — e.g., a cast integer, a config string bound into the enum, or a newly added enum member the switch doesn't cover.

Common situations: Site or tenant settings store an unsupported calendar value (e.g., Hebrew/Hijri requested by content but not mapped); upgrading code where a new CalendarName member was added without updating the switch; invalid enum parsing from user input.

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AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/0739b8ea949cf047. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore/OrchardCore/Localization/BclCalendars.cs:26

    public static readonly Calendar Hebrew = new HebrewCalendar();
    public static readonly Calendar Hijri = new HijriCalendar();
    public static readonly Calendar Gregorian = new GregorianCalendar();
    public static readonly Calendar Julian = new JulianCalendar();
    public static readonly Calendar Persian = new PersianCalendar();
    public static readonly Calendar UmAlQura = new UmAlQuraCalendar();

    public static CalendarSystem GetCalendarByName(CalendarName calendarName) =>
        calendarName switch
        {
            CalendarName.Hebrew => CalendarSystem.HebrewCivil,
            CalendarName.Hijri => CalendarSystem.IslamicBcl,
            CalendarName.Gregorian => CalendarSystem.Iso,
            CalendarName.Julian => CalendarSystem.Julian,
            CalendarName.Persian => CultureInfo.CurrentUICulture.Calendar.IsLeapYear(1)
            ? CalendarSystem.PersianSimple
            : CalendarSystem.PersianAstronomical,
            CalendarName.UmAlQura => CalendarSystem.UmAlQura,
            _ => throw new NotSupportedException($"The calendar is not supported."),
        };

    public static CalendarName GetCalendarName(Calendar calendar)
    {
        ArgumentNullException.ThrowIfNull(calendar);

        var calendarType = calendar.GetType();
        if (calendarType == typeof(GregorianCalendar))
        {
            return CalendarName.Gregorian;
        }
        else if (calendarType == typeof(HebrewCalendar))
        {
            return CalendarName.Hebrew;
        }
        else if (calendarType == typeof(HijriCalendar))
        {
            return CalendarName.Hijri;

View on GitHub (pinned to 4306c0717f)