How to include your ownCloud calendar into Outlook (read-only)

Say you have your contacts and calendar synchronised via your own private or trusted ownCloud instance. But then at your workplace, you have to use Outlook for your work stuff. Then there is the occasional late appointment, and you run into collisions because you did not look at your private calendar before accepting a meeting invitation. What to do? Wouldn’t it be nice to see your private calendar as an overlay directly in Outlook?

Search no further, the solution is here (shamelessly summarised and updated to my current OC 9.0.1 setup from the ownCloud forum thread Owncloud and Outlook):

The key is to append ?export to the CalDAV-URL that can be copied from the calendar web application.

  1. Log in to the ownCloud calendar web app
  2. Click on the settings menu (gears symbol)
  3. Copy the URL under the heading “Primary CalDAV address” and append your username and the calendar name (in lowercase) and append the export suffix: PRIMARYADDRESS/YourUserName/personal?export
  4. In Microsoft Outlook change to the calendar view
  5. In the Home tab click on “Open Calendar” and select “From Internet…”
  6. Paste the location the calendar, that you created in step 3 above
  7. Click “OK” to add the calendar
  8. Profit! (Hu?)

However, I found that this included calendar seems to be incredibly fragile. Although my ownCloud instance should be always available, the sync sometimes seems to fail silently, leading to an empty private calendar. Repeating the above steps to re-add the calendar sometimes remedies the situation for weeks, sometimes only for days.

In case you can install Add-Ins, the actively developed (as of 2016) Outlook CalDav Synchronizer offers a more reliable, and as far as I know, two-way sync from and to your ownCloud server.