Does anyone have CalDAV, and CardDAV working with Thunderbird? I am trying with Thunderbird 38.2.0, and Lightning Addon 18.104.22.168. When I add a new calendar in Lightning, and choose "Network Location" -> "CalDAV" and put in the location "Direct URLs for Calendars" it adds the calendar, but when I try to add a calendar event it says: Error code: MODIFICATION_FAILED Status Code: 2147746065, The request cannot be processed. Server Replied with 500 If I try and add the "Advanced Manual Settings" Server address in the location field it says "The calendar is momentarily not available" and it does not appear to function. I have already open the related TCP ports. 2079, and 2080.