calcom/cal.diy · error · BadRequestException

Attendee with this email can't book because the maximum numb

Error message

Attendee with this email can't book because the maximum number of active bookings has been reached.

What it means

Thrown by handleBookingError when error.message === 'booker_limit_exceeded_error'. BadRequestException (HTTP 400). The attendee's email has reached the event type's per-attendee active-booking limit, so a new booking is refused. No reschedule context is attached in this branch (that is error 332).

Source

Thrown at apps/api/v2/src/platform/bookings/2024-08-13/services/errors.service.ts:52

  handleBookingError(error: unknown, bookingTeamEventType: boolean): never {
    const hostsUnavaile = "One of the hosts either already has booking at this time or is not available";

    if (error instanceof Error) {
      if (error.message === "no_available_users_found_error") {
        if (bookingTeamEventType) {
          throw new BadRequestException(hostsUnavaile);
        }
        throw new BadRequestException("User either already has booking at this time or is not available");
      } else if (error.message === "booking_time_out_of_bounds_error") {
        throw new BadRequestException(
          `The event type can't be booked at the "start" time provided. This could be because it's too soon (violating the minimum booking notice) or too far in the future (outside the event's scheduling window). Try fetching available slots first using the GET /v2/slots endpoint and then make a booking with "start" time equal to one of the available slots.`
        );
      } else if (error.message === "Attempting to book a meeting in the past.") {
        throw new BadRequestException("Attempting to book a meeting in the past.");
      } else if (error.message === "hosts_unavailable_for_booking") {
        throw new BadRequestException(hostsUnavaile);
      } else if (error.message === "booker_limit_exceeded_error") {
        throw new BadRequestException(
          "Attendee with this email can't book because the maximum number of active bookings has been reached."
        );
      } else if (error.message === "booker_limit_exceeded_error_reschedule") {
        const errorData =
          "data" in error ? (error.data as { rescheduleUid: string }) : { rescheduleUid: undefined };
        let message =
          "Attendee with this email can't book because the maximum number of active bookings has been reached.";
        if (errorData?.rescheduleUid) {
          message += ` You can reschedule your existing booking (${errorData.rescheduleUid}) to a new timeslot instead.`;
        }
        throw new BadRequestException(message);
      }
    }
    throw error;
  }
}

View on GitHub (pinned to 176037d0af)

Solutions

  1. Cancel one of the attendee's existing active bookings before creating a new one.
  2. Raise the event type's bookerLimit if concurrent bookings should be allowed.
  3. Check the attendee's active booking count via GET /v2/bookings?attendeeEmail=... before attempting to book.
  4. Offer a reschedule of an existing booking instead (which routes through the 332 branch).

Example fix

// before
await api.post('/v2/bookings', { ... attendee: { email: 'a@b.com' } });

// after
const active = await api.get(`/v2/bookings?attendeeEmail=a@b.com&status=upcoming`);
if (active.data.length >= bookerLimit) {
  await api.delete(`/v2/bookings/${active.data[0].uid}`);
}
await api.post('/v2/bookings', { ... attendee: { email: 'a@b.com' } });
Defensive patterns

Strategy: validation

Validate before calling

const active = await api.get(`/v2/bookings?attendeeEmail=${encodeURIComponent(email)}&status=upcoming`);
if (active.data.length >= bookerLimit) throw new Error('booker limit reached — cancel an existing booking first');

Type guard

null

Try / catch

try { await api.post('/v2/bookings', body); }
catch (e) {
  if (e.response?.status === 400 && /maximum number of active bookings/.test(e.response.data.message)) {
    /* offer cancel-or-reschedule flow */
  } else throw e;
}

Prevention

When it happens

Trigger: Booking an event type that enforces a maximum number of active bookings per attendee email (bookerLimit), when the attendee already holds that many active (non-cancelled) bookings. Typical for classes, seated events, or limited-trial event types.

Common situations: Attendee tries to double-book a limited class; previous bookings were not cancelled before booking a new slot; bookerLimit was lowered after earlier bookings were made; attendee email reused across test accounts hitting the same limit.

Related errors

AI-assisted analysis of calcom/cal.diy@176037d0af (2026-08-12). Data as JSON: /api/errors/baf72069e22d7aef. Report an issue: GitHub.