I'm referring to https://central.owncloud.org/t/owncloud-10-0-4-4-davfs-issue/10741.
After updating my ownCloud instance to 10.0.4 CalDAV-/CarDAV-Sync with cellphone doesn't work anymore. However, synchronizing from MS Outlook with https://sourceforge.net/projects/outlookcaldavsynchronizer/ still works properly.
As already announced this issue should be fixed in ownCloud 10.0.5. Do you have any workaround available that fixes my issue in ownCloud 10.0.4?
If i'm clicking on your posted link i'm seeing a linked workaround when scrolling down.
I've already seen this workaround but was quenched by the info about "/apps/dav/lib/Connector/Sabre/". That I didn't find in my ownCloud instance.
I did now implement the following change:
diff --git a/apps/dav/lib/Server.php b/apps/dav/lib/Server.php
- $this->server->addPlugin(new CorsPlugin(\OC::$server->getUserSession()));
+ //$this->server->addPlugin(new CorsPlugin(\OC::$server->getUserSession()));
And now it works! 
the correct fix is in here https://github.com/owncloud/core/pull/29874 - will be shipped with 10.0.5 in January