$ curl -vX OPTIONS -u $username:$password https://caldav.yandex.ru
* Rebuilt URL to: https://caldav.yandex.ru/
* Adding handle: conn: 0x1faadc0
* Adding handle: send: 0
* Adding handle: recv: 0
* Curl_addHandleToPipeline: length: 1
* - Conn 0 (0x1faadc0) send_pipe: 1, recv_pipe: 0
* About to connect() to caldav.yandex.ru port 443 (#0)
* Trying 93.158.134.59...
* Connected to caldav.yandex.ru (93.158.134.59) port 443 (#0)
* Initializing NSS with certpath: sql:/etc/pki/nssdb
* CAfile: /etc/pki/tls/certs/ca-bundle.crt
CApath: none
* SSL connection using SSL_RSA_WITH_RC4_128_SHA
* Server certificate:
* subject: E=pki@yandex-team.ru,CN=caldav.yandex.ru,ST=Russian Federation,L=Moscow,OU=ITO,O=Yandex LLC,C=RU
* start date: Nov 28 14:26:26 2013 GMT
* expire date: Nov 27 14:26:26 2016 GMT
* common name: caldav.yandex.ru
* issuer: CN=Certum Level IV CA,OU=Certum Certification Authority,O=Unizeto Technologies S.A.,C=PL
* Server auth using Basic with user 'caldavtest@yandex.ru'
> OPTIONS / HTTP/1.1
> Authorization: Basic XXXXXXXXXXXXXXXXXXXXXXX
> User-Agent: curl/7.32.0
> Host: caldav.yandex.ru
> Accept: */*
>
< HTTP/1.1 200 OK
* Server nginx is not blacklisted
< Server: nginx
< Date: Sat, 15 Mar 2014 11:52:02 GMT
< Content-Length: 0
< Connection: keep-alive
< X-Request-Id: MX4MpOz1_01g
< DAV: 1,addressbook,calendar-access,calendar-auto-schedule,calendar-availability,calendar-schedule,calendar-proxy,calendarserver-private-comments,calendarserver-principal-property-search
< Allow: OPTIONS, GET, HEAD, POST, TRACE, PROPFIND, PROPPATCH, MKCOL, COPY, PUT, DELETE, MOVE, LOCK, UNLOCK
< MS-Author-Via: DAV
<
* Connection #0 to host caldav.yandex.ru left intact
As you can see, there’s no Allow: REPORT
although this is required for CalDAV/CardDAV synchronization.
This issue is similar to https://github.com/rfc2822/davdroid/issues/87
I have sent a bug report via the Yandex contact form.