Locker, vorwärts, schwerelos, abschweifend, schließe die Augen und Du weißt immer noch, dass es in die richtige Richtung geht.
If they can get you asking the wrong questions, they don’t have to worry about answers.
(Thomas Pynchon – Gravity’s Rainbow)
The apps contacts and calendar not working after the upgrade? I had the same problem. Found some help here: https://github.com/owncloud/core/issues/14033
To get my contacts app working again I had to delete it from the server via ftp and upload the upgraded app from here: https://apps.owncloud.com/content/show.php/Contacts+8.0?content=168708
That could work for the calendar app, too, but I didin’t test it. Download it here: https://apps.owncloud.com/content/show.php/Calendar+8.0?content=168707