### Steps to reproduce

1. Login as user able to manage calendars and create work packages
2. Go to a project and open Calendars module
3. Create a calendar (if there is not one already)
4. Click on a date in the calendar in order to create an event
5. Begin of the insertionFill in only startEnd of the insertion Begin of the deletion Start and endEnd of the deletion date Begin of the insertion(while finish date shouldEnd of the insertion Begin of the deletion willEnd of the deletion be Begin of the insertionempty)
6. Try to dragEnd of the insertion Begin of the deletion both pre-filled withEnd of the deletion the Begin of the insertionevent to some otherEnd of the insertion date Begin of the insertioninEnd of the insertion Begin of the deletion you clicked on, so just enterEnd of the deletion the Begin of the insertioncalendarEnd of the insertion Begin of the deletion title (or any other required field) and click SaveEnd of the deletion

### What is the buggy behavior?

* Begin of the insertionThere is an error sayingEnd of the insertion Begin of the deletion The event does not appear in the calendar until we reload the page
* Even if we change the dates (for example, change the finish date soEnd of the deletion that Begin of the insertionFinish dateEnd of the insertion Begin of the deletion event takes more than 1 day), the changeEnd of the deletion is Begin of the insertionmissingEnd of the insertion Begin of the deletion not visible until the reloadEnd of the deletion

### What is the expected behavior?

1. Begin of the insertion


End of the insertion Begin of the deletion Event should be visible in the calendar upon creation without reloading the page (if that is possible)
2. Changes on the dates should be reflected immediately too (if possible)

End of the deletion **OpenProject version**

_13.0_

**Browser**

* [x] Chrome
* [ ] Firefox
* [ ] Safari
* [ ] Mobile Safari
* [ ] Other (please specify)