It is possible to edit an event with registrants, however, it is not possible to edit all the fields.
You will find below the exhaustive list of the fields which you can not edit in your event:
- The type of registration
- Decrease the maximum number of applicants below the current number of registrants
- Ask the candidates for additional information / ask new questions
- Edit the event to make it with/without slots
- Make slots mandatory
- Make attendance mandatory
- Enable manual validation of registrants
Events with slots
Once there are students enrolled in a slot, everything can be changed except for the slot time info (ie the maximum number of registrants, description, title). Any update of the title or the description of a slot with registered users then triggers the sending of an email to all registered students.