Error while syncing calendar with emacs orgmode

I use the combination owncloud and emacs org-mode for years now.

for syncing my calendar data i use the following emacs plugin:

I want to migrate to nextcloud but with nextcloud i cant sync the calendar.

first i opened a ticket for org-caldav but there is no response.
with owncloud there is no error while syncing…

httpx:// (please replace x bei s in in protocol)

what is the difference here?

In my opinion it must be somithing with the cookie handling of nextcloud… nobody can help?