I have a calendar working, so it seems, but when I try to connect to it from Thunderbird and likes I fail. Thunderbird just keeps asking to authenticate, which I do using same credential I login to Owncloud. As caldav url I use the one Owncloud gives out when click "Link", but I also tried iCal from settings.
Now that I've fixed OC logging, in logs when I try to connect in a web browser to URL of the caldav I see:
{"reqId":"Whh1EMzVRPxavlJ6IPQ9cgAAAAk","remoteAddr":"172.24.154.138","app":"webdav","message":"Exception: {\"Message\":\"HTTP\\/1.1 401 No 'Authorization: Basic' header found. Either the client didn't send one, or the server is mis-configured, No 'Authorization: Basic' header found. Either the client didn't send one, or the server is mis-configured\",\"Exception\":\"Sabre\\DAV\\Exception\\NotAuthenticated\",\"Code\":0,\"Trace\":\"#0 [internal function]: Sabre\\DAV\\Auth\\Plugin->beforeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#1 \\/usr\\/share\\/php\\/Sabre\\/Event\\/EventEmitterTrait.php(105): call_user_func_array(Array, Array)\n#2 \\/usr\\/share\\/php\\/Sabre\\/DAV\\/Server.php(446): Sabre\\Event\\EventEmitter->emit('beforeMethod', Array)\n#3 \\/usr\\/share\\/php\\/Sabre\\/DAV\\/Server.php(248): Sabre\\DAV\\Server->invokeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#4 \\/usr\\/share\\/owncloud.clustered\\/apps\\/dav\\/lib\\/Server.php(178): Sabre\\DAV\\Server->exec()\n#5 \\/usr\\/share\\/owncloud.clustered\\/apps\\/dav\\/appinfo\\/v2\\/remote.php(30): OCA\\DAV\\Server->exec()\n#6 \\/usr\\/share\\/owncloud.clustered\\/remote.php(164): require_once('\\/usr\\/share\\/ownc...')\n#7 {main}\",\"File\":\"\\/usr\\/share\\/php\\/Sabre\\/DAV\\/Auth\\/Plugin.php\",\"Line\":188,\"User\":false}","level":0,"time":"2017-11-24T19:37:52+00:00","method":"GET","url":"\/owncloud\/remote.php\/dav\/calendars\/pe\/personal\/","user":"--"}
And I think that above logged info is identical when I try with Thunderbird.