Sorry for the noise. It was a problem with one of the accounts.
Now it works as expected. Only one account needed and both cardav and caldav can connect. Tasks also work.
Contacts' birthday in Calendar app
I just discovered that Android can use information stored in your contacts like birthdays and display it in your calendar app. But it seems that it only can use Google contacts.
I don’t know if this a limitation of the calendar app or not, but, as Davdroid knows both my calendars and contacts, do you think it should be possible to use contacts’ birthday information and display it in the calendars? maybe having an option to create a ‘fake’ calendar which only retrieve information from contacts.
Thanks for the job done on this app which enables to free Android from Google.
Birthdays are synced by DAVdroid into the Android address book. Displaying this data in a fake calendar is not the task of DAVdroid – you may use an app like Birthday Calendar Adapter for that.
I didn’t know Birthday Calendar Adapter but it seems to do exactly what I wanted. Thanks for your answer.