I was looking into the Console messages that showed up:
This is what I'm getting in Console from Thunderbird Lightning Calendar
9/4/12 4:51:49 PM [0x0-0x11e11e].org.mozilla.thunderbird[2047] Warning: There has been an error reading data for calendar: [XXXx]. However, this error is believed to be minor, so the program will attempt to continue. Error code: DAV_NOT_DAV. Description: The resource at https://www.google.com/calendar/dav/[...]/events is either not a DAV collection or not available
This is what I'm getting in Console from iCal
9/4/12 4:58:55 PM iCal[2119] CalDAV CalDAVAccountRefreshQueueableOperation failed: status 'HTTP/1.1 405 Method Not Allowed' request:
<?xml version="1.0" encoding="utf-8"?>
<x0:propfind xmlns:x2="http://calendarserver.org/ns/" xmlns:x1="urn:ietf:params:xml:ns:caldav" xmlns:x0="DAV:">
<x0:prop>
<x1:calendar-home-set/>
<x1:calendar-user-address-set/>
<x1:schedule-inbox-URL/>
<x1:schedule-outbox-URL/>
<x2:dropbox-home-URL/>
<x2:notifications-URL/>
<x0:displayname/>
</x0:prop>
</x0:propfind>
... response:
HTTP/1.1 405 Method Not Allowed
Content-Type: text/html; charset=UTF-8
Content-Length: 1034
Date: Tue, 04 Sep 2012 15:58:55 GMT
Server: GFE/2.0
<!DOCTYPE html>
<html lang=en>
<meta charset=utf-8>
<meta name=viewport content="initial-scale=1, minimum-scale=1, width=device-width">
<title>Error 405 (Method Not Allowed)!!1</title>
<style>
*{margin:0;padding:0}html,code{font:15px/22px arial,sans-serif}html{background:#fff;color:#222;padding:15px}body{margin:7% auto 0;max-width:390px;min-height:180px;padding:30px 0 15px}* > body{background:url(//www.google.com/images/errors/robot.png) 100% 5px no-repeat;padding-right:205px}p{margin:11px 0 22px;overflow:hidden}ins{color:#777;text-decoration:none}a img{border:0}@media screen and (max-width:772px){body{background:none;margin-top:0;max-width:none;padding-righ t:0}}
</style>
<a href=//www.google.com/><img src=//www.google.com/images/errors/logo_sm.gif alt=Google></a>
<p><b>405.</b> <ins>That’s an error.</ins>
<p>The request method <code>PROPFIND</code> is inappropriate for the URL <code>/calendar/dav/[...]/user/</code>. <ins>That’s all we know.</ins>
So this is certainly Google doing something to their servers...
