As of March 7, 2015, ownCloud 8 does not ship with the Tasks app. The developer is working to make it ship with ownCloud 8 by default, but in the mean time, you can easily enable it yourself. Just follow the instructions from the github Tasks page:
- Enable the ownCloud Calendar app. It will be located under Recommended or Not Enabled.
- Run the following code on your computer with ownCloud
cd /var/www/owncloud/app
git clone https://github.com/owncloud/tasks/ - Enable the ownCloud Task app:
Enjoy your tasks!
Sources:
Man and Keyboard 
Hi Brian,
Thank you for your tasks tutorial. Everything worked fine like you descibed it. But when I open tasks in owncloud I can see only two columns and there is not much to edit. The picture on the owncloud side says that you can add tasks in calendar etc.:
https://apps.owncloud.com/content/show.php/Tasks?content=164356&PHPSESSID=aipq9sirrcano0c34ldr6mgcp3
Do you know how I can get the third right column and how to connect tasks with calendar?
Thank you and kind regards from Frankfurt /Germany
Harald
In my tasks, I have the 1st column which is the list of task types (completed, important) and task lists. The second column are the tasks in the selected list. When you click on the task, a 3rd column will appear giving you more options for the task.
Tasks and calendar are tied together. Each calendar has a set of tasks associated with it. If you add a new task list, you are actually making a new calendar. You need to have the Calendar app installed for Tasks to work as well.
Thank you for your reply.I think this is the point: When I click on a task no 3rd column appears. I can only edit the 2nd column.
>> Tasks and calendar are tied together. Each calendar has a set of tasks associated with it.
This isn’t true in my installation though I installed the recent LAMP etc.
Perhaps I’ll have to wait for the next update.
Thanks again
Harald
Doesn’t seem to work with OC8.1, does it ?
Tasks are working for me in 8.1. Do you have an error?