OS X Contacts (Mountain Lion) with CardDav - "CoreDAVHTTPStatusErrorDomain error 500" I've recently setup a CardDav account with a hosted Atmail Cloud account. It works perfectly on iOS, and seems to pull in some of the contacts, however every time Contacts re-syncs I am getting the following error:

    9/20/12 5:19:24.622 PM Contacts[785]: [CardDAVPlugin-ERROR] -_handleCompletedAction: Error Domain=CoreDAVHTTPStatusErrorDomain Code=500 "The operation couldn’t be completed. (CoreDAVHTTPStatusErrorDomain error 500.)" UserInfo=0x7ff1a6409cb0 {CoreDAVHTTPHeaders=&lt;CFBasicHash 0x7ff1a61475b0 [0x7fff73a56fd0]&gt;{type = immutable dict, count = 8,
entries =&gt;
    0 : Case Insensitive Key: Server = &lt;CFString 0x7ff1a66096c0 [0x7fff73a56fd0]&gt;{contents = "Apache/2.2.15 (CentOS)"}
    1 : Case Insensitive Key: X-Powered-By = &lt;CFString 0x7ff1a64bc030 [0x7fff73a56fd0]&gt;{contents = "PHP/5.3.3"}
    2 : Case Insensitive Key: Connection = &lt;CFString 0x7ff1a64aa4a0 [0x7fff73a56fd0]&gt;{contents = "close"}
    3 : Case Insensitive Key: Content-Type = &lt;CFString 0x7ff1a661ccb0 [0x7fff73a56fd0]&gt;{contents = "application/xml; charset=utf-8"}
    6 : Case Insensitive Key: Date = &lt;CFString 0x7ff1a4efb270 [0x7fff73a56fd0]&gt;{contents = "Thu, 20 Sep 2012 21:19:24 GMT"}
    8 : Case Insensitive Key: Content-Encoding = &lt;CFString 0x7ff1a64a7220 [0x7fff73a56fd0]&gt;{contents = "gzip"}
    10 : Case Insensitive Key: Content-Length = &lt;CFString 0x7ff1a6149f80 [0x7fff73a56fd0]&gt;{contents = "187"}
    12 : Case Insensitive Key: Vary = &lt;CFString 0x7ff1a665dd70 [0x7fff73a56fd0]&gt;{contents = "Accept-Encoding"}
}
}


Is this a problem with the CardDav server or Contacts? Anyone run into this issue before?
The response says the the error is when communicating with the 3rd party server (since the Mac isn't CentOS obviously) and that there was an error on the server side (type 500)

The 5xx range of HTTP response codes are for server side errors, basically there was an error, we couldn't do anything and we are closing the connection.