How to synch tasks from Linux Desktop?

OS: Ubuntu 18.10
DE: LXDE

I’m trying to synch the Nextcloud tasks from Linux Desktop. Within Evolution I am able to create CalDAV task lists that are synchronized with my NextCloud task lists, but apparently only in reading mode. When I try to create a new task or edit an existing one I get following error “Cannot create calendar object: SQLite error code ‘8’: attempt to write a readonly database”.

I’m using a Nextcloud instance hosted by a 3rd party, ocloud.de.

I could try to set up a Nextcloud account with Gnome Online Accounts, but so far I have not managed to get this to work (submit button to create the account from within Gnome Control Center is not shown, maybe a bug specific to the LXDE DE).

Any ideas?

I believe to have found the solution meanwhile.

I logged in using the Gnome Desktop Environment, and created a Nextcloud account with Gnome Online Accounts (login button was available here). Then in the Tasks panel of Evolution a Task subtree appears for the Nextcloud account, containing all the Task lists created through the Nextcloud web interface.

I’m not sure why, but initially I still couldn’t add or modify tasks, with attempts resulting in various error messages. However, after logging out and logging in again using the LXDE DE, I am now able to add and modify tasks (I should ideally try to log in with Gnome DE again to see if the inability to modify and add tasks in that DE persists).

The only thing I’m not able to from Evolution is to create a new task list. That still needs to be done through the Web interface. And that’s absolutely not an issue for me.