Your reservation for name ?> has been overbooked by getFullName() ?> and therefore has become invalid. Reservation data: booking_user instanceof User): ?> - Booking person: booking_user->getFullName() ?> assigned_user instanceof User) && $reservation->range_id != $reservation->booking_user_id): ?> - Assigned person: assigned_user->getFullName() ?> The reserved time ranges were: getTimeIntervals() ?> - begin) ?> - end) ?> description): ?> Booking text: description ?>