The problem still persist in Ubuntu 17.10. Installing gnome-control- center and evolution didn't work for me.
When I try to add online calendar (Settings -> Add -> From Web) in "Add calendar" dialog, button "Add" stays disabled when I enter URL. If I download the calendar and add it via "From file" method, everything works. % sudo apt-get install gnome-control-center evolution Reading package lists... Done Building dependency tree Reading state information... Done gnome-control-center is already the newest version (1:3.26.1-0ubuntu4). evolution is already the newest version (3.26.1-1). 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. % apt-cache policy gnome-calendar gnome-calendar: Installed: 3.26.2-1 Candidate: 3.26.2-1 Version table: *** 3.26.2-1 500 500 http://ie.archive.ubuntu.com/ubuntu artful/main amd64 Packages 100 /var/lib/dpkg/status % lsb_release -rd Description: Ubuntu 17.10 Release: 17.10 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1580635 Title: Nothing happens when trying to add online calendar To manage notifications about this bug go to: https://bugs.launchpad.net/hundredpapercuts/+bug/1580635/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs