Error occured while writing shared agenda

I’m running ubuntu 22.04 and thunderbird 115.5.0
I get the “error occured while writing in the agenda” when trying to create a new event.
I’m able to create new events from other devices such as android and other unbuntu-thunderbird machines
I wonder what thunderbird parameters could prevent writing.
Thanks for helping

I wonder what nextcloud parameter would prevent writing an event through thunderbird’s agenda